sim: switch to AC_CHECK_HEADERS_ONCE

This avoids duplicate tests for headers between common m4, arches,
and any other sources that would trigger header tests.

51 files changed, 1580 insertions, 1698 deletions

diff --git a/sim/ChangeLog b/sim/ChangeLog
index 6ee80b4..8c6f027 100644
--- a/sim/ChangeLog
+++ b/sim/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* m4/sim_ac_common.m4: Change AC_CHECK_HEADERS to
+	AC_CHECK_HEADERS_ONCE, merge calls, and sort args.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* m4/sim_ac_common.m4: Change AC_CHECK_FUNCS to AC_CHECK_FUNCS_ONCE,
 	merge calls, and sort args.
 
diff --git a/sim/aarch64/configure b/sim/aarch64/configure
index aec76c8..d6b6477 100755
--- a/sim/aarch64/configure
+++ b/sim/aarch64/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/arm/configure b/sim/arm/configure
index 11da849..8715cd4 100755
--- a/sim/arm/configure
+++ b/sim/arm/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/avr/configure b/sim/avr/configure
index 4488524..461f80a 100755
--- a/sim/avr/configure
+++ b/sim/avr/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/bfin/ChangeLog b/sim/bfin/ChangeLog
index 64c71f9..a2653d4 100644
--- a/sim/bfin/ChangeLog
+++ b/sim/bfin/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure.ac: Change AC_CHECK_HEADERS to AC_CHECK_HEADERS_ONCE.
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* configure.ac: Change AC_CHECK_FUNCS to AC_CHECK_FUNCS_ONCE and
 	delete mmap & munmap.
 	* configure: Regenerate.
diff --git a/sim/bfin/configure b/sim/bfin/configure
index e1692b1..35ddcc9 100755
--- a/sim/bfin/configure
+++ b/sim/bfin/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2312,6 +2313,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -2330,6 +2340,11 @@ as_fn_append ac_func_list " setuid"
 as_fn_append ac_func_list " setgid"
 as_fn_append ac_func_list " kill"
 as_fn_append ac_func_list " pread"
+as_fn_append ac_header_list " linux/if_tun.h"
+as_fn_append ac_header_list " linux/mii.h"
+as_fn_append ac_header_list " linux/types.h"
+as_fn_append ac_header_list " net/if.h"
+as_fn_append ac_header_list " sys/ioctl.h"
 # Check that the precious variables saved in the cache have kept the same
 # value.
 ac_cache_corrupted=false
@@ -3907,6 +3922,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7334,56 +7384,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -12304,25 +12304,16 @@ fi
 
 
 
-for ac_header in  \
-	linux/if_tun.h \
-	linux/mii.h \
-	linux/types.h \
-	net/if.h \
-	sys/ioctl.h \
-	sys/mman.h \
 
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
 
-fi
 
-done
+
+
+
+
+
+
+
 
 
 
diff --git a/sim/bfin/configure.ac b/sim/bfin/configure.ac
index 6b15b77..cedd967 100644
--- a/sim/bfin/configure.ac
+++ b/sim/bfin/configure.ac
@@ -43,14 +43,14 @@ SIM_AC_OPTION_HARDWARE(yes,,\
 )
 
 AC_CHECK_FUNCS_ONCE([getuid getgid geteuid getegid setuid setgid kill pread])
-AC_CHECK_HEADERS([ \
-	linux/if_tun.h \
-	linux/mii.h \
-	linux/types.h \
-	net/if.h \
-	sys/ioctl.h \
-	sys/mman.h \
-])
+AC_CHECK_HEADERS_ONCE(m4_flatten([
+	linux/if_tun.h
+	linux/mii.h
+	linux/types.h
+	net/if.h
+	sys/ioctl.h
+	sys/mman.h
+]))
 
 PKG_PROG_PKG_CONFIG
 PKG_CHECK_MODULES(SDL, sdl, [
diff --git a/sim/bpf/configure b/sim/bpf/configure
index ab02f8c..c6c447c 100755
--- a/sim/bpf/configure
+++ b/sim/bpf/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2302,6 +2303,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3889,6 +3899,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7316,56 +7361,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11268,7 +11263,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11271 "configure"
+#line 11266 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11374,7 +11369,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11377 "configure"
+#line 11372 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/cr16/configure b/sim/cr16/configure
index b044655..8c28099 100755
--- a/sim/cr16/configure
+++ b/sim/cr16/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/cris/ChangeLog b/sim/cris/ChangeLog
index ece075e..fefb74c 100644
--- a/sim/cris/ChangeLog
+++ b/sim/cris/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure.ac: Change AC_CHECK_HEADERS to AC_CHECK_HEADERS_ONCE.
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* configure: Regenerate.
 
 2021-04-12  Mike Frysinger  <vapier@gentoo.org>
diff --git a/sim/cris/configure b/sim/cris/configure
index 4c89d99..a1f6947 100755
--- a/sim/cris/configure
+++ b/sim/cris/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2303,6 +2304,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -2313,6 +2323,9 @@ as_fn_append ac_func_list " posix_fallocate"
 as_fn_append ac_func_list " sigaction"
 as_fn_append ac_func_list " time"
 as_fn_append ac_func_list " truncate"
+as_fn_append ac_header_list " sys/param.h"
+as_fn_append ac_header_list " sys/select.h"
+as_fn_append ac_header_list " sys/socket.h"
 # Check that the precious variables saved in the cache have kept the same
 # value.
 ac_cache_corrupted=false
@@ -3890,6 +3903,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7317,56 +7365,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11269,7 +11267,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11272 "configure"
+#line 11270 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11375,7 +11373,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11378 "configure"
+#line 11376 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11924,18 +11922,12 @@ _ACEOF
 
 
 # For dv-rv and rvdummy.
-for ac_header in sys/socket.h sys/select.h sys/param.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
 
-fi
 
-done
+
+
+
+
 
 
 
diff --git a/sim/cris/configure.ac b/sim/cris/configure.ac
index 1eee817..56afe58 100644
--- a/sim/cris/configure.ac
+++ b/sim/cris/configure.ac
@@ -5,7 +5,11 @@ AC_CONFIG_MACRO_DIRS([../m4 ../.. ../../config])
 SIM_AC_COMMON
 
 # For dv-rv and rvdummy.
-AC_CHECK_HEADERS(sys/socket.h sys/select.h sys/param.h)
+AC_CHECK_HEADERS_ONCE(m4_flatten([
+  sys/param.h
+  sys/select.h
+  sys/socket.h
+]))
 
 SIM_AC_OPTION_ENDIAN(LITTLE)
 SIM_AC_OPTION_ALIGNMENT(NONSTRICT_ALIGNMENT)
diff --git a/sim/d10v/configure b/sim/d10v/configure
index 3133e3b..cb57e7f 100755
--- a/sim/d10v/configure
+++ b/sim/d10v/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/erc32/configure b/sim/erc32/configure
index d9b685d..b31ddda 100755
--- a/sim/erc32/configure
+++ b/sim/erc32/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2285,6 +2286,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3872,6 +3882,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7299,56 +7344,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11251,7 +11246,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11254 "configure"
+#line 11249 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11357,7 +11352,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11360 "configure"
+#line 11355 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/example-synacor/configure b/sim/example-synacor/configure
index 1405972..1ee8fb7 100755
--- a/sim/example-synacor/configure
+++ b/sim/example-synacor/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/frv/configure b/sim/frv/configure
index 298b815..2714257 100755
--- a/sim/frv/configure
+++ b/sim/frv/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2306,6 +2307,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3893,6 +3903,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7320,56 +7365,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11272,7 +11267,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11275 "configure"
+#line 11270 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11378,7 +11373,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11381 "configure"
+#line 11376 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/ft32/configure b/sim/ft32/configure
index c3a092c..106c409 100755
--- a/sim/ft32/configure
+++ b/sim/ft32/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/h8300/ChangeLog b/sim/h8300/ChangeLog
index d900442..de7bec7 100644
--- a/sim/h8300/ChangeLog
+++ b/sim/h8300/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure.ac: Change AC_CHECK_HEADERS to AC_CHECK_HEADERS_ONCE.
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* configure: Regenerate.
 
 2021-04-12  Mike Frysinger  <vapier@gentoo.org>
diff --git a/sim/h8300/configure b/sim/h8300/configure
index c331313..c3fc783 100755
--- a/sim/h8300/configure
+++ b/sim/h8300/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -2299,6 +2309,7 @@ as_fn_append ac_func_list " posix_fallocate"
 as_fn_append ac_func_list " sigaction"
 as_fn_append ac_func_list " time"
 as_fn_append ac_func_list " truncate"
+as_fn_append ac_header_list " sys/param.h"
 # Check that the precious variables saved in the cache have kept the same
 # value.
 ac_cache_corrupted=false
@@ -3876,6 +3887,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7349,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11251,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11254 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11357,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11360 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12098,17 +12094,8 @@ $as_echo "${WARN_CFLAGS} ${WERROR_CFLAGS}" >&6; }
 fi
 
 
-for ac_header in sys/param.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "sys/param.h" "ac_cv_header_sys_param_h" "$ac_includes_default"
-if test "x$ac_cv_header_sys_param_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_SYS_PARAM_H 1
-_ACEOF
 
-fi
 
-done
 
 
 
diff --git a/sim/h8300/configure.ac b/sim/h8300/configure.ac
index 177f7de..8dc33c4 100644
--- a/sim/h8300/configure.ac
+++ b/sim/h8300/configure.ac
@@ -8,6 +8,6 @@ SIM_AC_OPTION_ENDIAN(BIG)
 SIM_AC_OPTION_ALIGNMENT(NONSTRICT_ALIGNMENT)
 SIM_AC_OPTION_WARNINGS(no)
 
-AC_CHECK_HEADERS(sys/param.h)
+AC_CHECK_HEADERS_ONCE(sys/param.h)
 
 SIM_AC_OUTPUT
diff --git a/sim/iq2000/ChangeLog b/sim/iq2000/ChangeLog
index cb67450..ee387d8 100644
--- a/sim/iq2000/ChangeLog
+++ b/sim/iq2000/ChangeLog
@@ -1,5 +1,9 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* Makefile.in (NL_TARGET): Define.
 	* iq2000.c: Include targ-vals.h.
 	(libgloss_syscall): Delete.
diff --git a/sim/iq2000/configure b/sim/iq2000/configure
index 875c631..5a3021a 100755
--- a/sim/iq2000/configure
+++ b/sim/iq2000/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2303,6 +2304,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3890,6 +3900,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7317,56 +7362,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11269,7 +11264,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11272 "configure"
+#line 11267 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11375,7 +11370,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11378 "configure"
+#line 11373 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/lm32/configure b/sim/lm32/configure
index 4a8f4a4..737d828 100755
--- a/sim/lm32/configure
+++ b/sim/lm32/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2303,6 +2304,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3890,6 +3900,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7317,56 +7362,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11269,7 +11264,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11272 "configure"
+#line 11267 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11375,7 +11370,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11378 "configure"
+#line 11373 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/m32c/ChangeLog b/sim/m32c/ChangeLog
index 26c7c98..ec483de 100644
--- a/sim/m32c/ChangeLog
+++ b/sim/m32c/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure.ac: Change AC_CHECK_HEADERS to AC_CHECK_HEADERS_ONCE.
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* Makefile.in (NL_TARGET): Define.
 	* syscalls.c: Change syscall.h include to targ-vals.h.
 	(m32c_syscall): Add TARGET_ prefix to all SYS_ constants.
diff --git a/sim/m32c/configure b/sim/m32c/configure
index aa106d2..0b06935 100755
--- a/sim/m32c/configure
+++ b/sim/m32c/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2282,6 +2283,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -2292,6 +2302,11 @@ as_fn_append ac_func_list " posix_fallocate"
 as_fn_append ac_func_list " sigaction"
 as_fn_append ac_func_list " time"
 as_fn_append ac_func_list " truncate"
+as_fn_append ac_header_list " termios.h"
+as_fn_append ac_header_list " netinet/in.h"
+as_fn_append ac_header_list " netinet/tcp.h"
+as_fn_append ac_header_list " sys/select.h"
+as_fn_append ac_header_list " sys/socket.h"
 # Check that the precious variables saved in the cache have kept the same
 # value.
 ac_cache_corrupted=false
@@ -3869,6 +3884,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7296,56 +7346,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -12000,18 +12000,16 @@ $as_echo "${WARN_CFLAGS} ${WERROR_CFLAGS}" >&6; }
 fi
 
 
-for ac_header in sys/select.h termios.h sys/socket.h netinet/in.h netinet/tcp.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
 
-fi
 
-done
+
+
+
+
+
+
+
+
 
 
 
diff --git a/sim/m32c/configure.ac b/sim/m32c/configure.ac
index 789bce4..a69fa12 100644
--- a/sim/m32c/configure.ac
+++ b/sim/m32c/configure.ac
@@ -25,6 +25,12 @@ SIM_AC_COMMON
 
 SIM_AC_OPTION_WARNINGS(no)
 
-AC_CHECK_HEADERS(sys/select.h termios.h sys/socket.h netinet/in.h netinet/tcp.h)
+AC_CHECK_HEADERS_ONCE(m4_flatten([
+  termios.h
+  netinet/in.h
+  netinet/tcp.h
+  sys/select.h
+  sys/socket.h
+]))
 
 SIM_AC_OUTPUT
diff --git a/sim/m32r/configure b/sim/m32r/configure
index be1b5ae..ec5f8f7 100755
--- a/sim/m32r/configure
+++ b/sim/m32r/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2305,6 +2306,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3892,6 +3902,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7319,56 +7364,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11271,7 +11266,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11274 "configure"
+#line 11269 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11377,7 +11372,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11380 "configure"
+#line 11375 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/m4/sim_ac_common.m4 b/sim/m4/sim_ac_common.m4
index 7845142..3cc9e87 100644
--- a/sim/m4/sim_ac_common.m4
+++ b/sim/m4/sim_ac_common.m4
@@ -52,10 +52,17 @@ ZW_GNU_GETTEXT_SISTER_DIR(../../intl)
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-AC_CHECK_HEADERS(unistd.h)
-AC_CHECK_HEADERS(sys/time.h sys/times.h sys/resource.h sys/mman.h)
-AC_CHECK_HEADERS(fcntl.h fpu_control.h)
-AC_CHECK_HEADERS(dlfcn.h sys/stat.h)
+AC_CHECK_HEADERS_ONCE(m4_flatten([
+  dlfcn.h
+  fcntl.h
+  fpu_control.h
+  unistd.h
+  sys/mman.h
+  sys/resource.h
+  sys/time.h
+  sys/times.h
+  sys/stat.h
+]))
 AC_CHECK_FUNCS_ONCE(m4_flatten([
   __setfpucw
   ftruncate
diff --git a/sim/m68hc11/configure b/sim/m68hc11/configure
index 4118c3e..1e465b3 100755
--- a/sim/m68hc11/configure
+++ b/sim/m68hc11/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2292,6 +2293,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3879,6 +3889,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7306,56 +7351,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11258,7 +11253,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11261 "configure"
+#line 11256 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11364,7 +11359,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11367 "configure"
+#line 11362 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/mcore/configure b/sim/mcore/configure
index f650776..5fac5b8 100755
--- a/sim/mcore/configure
+++ b/sim/mcore/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/microblaze/configure b/sim/microblaze/configure
index 11da849..8715cd4 100755
--- a/sim/microblaze/configure
+++ b/sim/microblaze/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/mips/configure b/sim/mips/configure
index d623dda..e0612f7 100755
--- a/sim/mips/configure
+++ b/sim/mips/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2322,6 +2323,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3909,6 +3919,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7336,56 +7381,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11288,7 +11283,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11291 "configure"
+#line 11286 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11394,7 +11389,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11397 "configure"
+#line 11392 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/mn10300/configure b/sim/mn10300/configure
index 410837e..ef463cb 100755
--- a/sim/mn10300/configure
+++ b/sim/mn10300/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2298,6 +2299,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3885,6 +3895,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7312,56 +7357,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11264,7 +11259,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11267 "configure"
+#line 11262 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11370,7 +11365,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11373 "configure"
+#line 11368 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/moxie/ChangeLog b/sim/moxie/ChangeLog
index 9621907..3d557ee 100644
--- a/sim/moxie/ChangeLog
+++ b/sim/moxie/ChangeLog
@@ -1,5 +1,9 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* Makefile.in (NL_TARGET): Define.
 	* interp.c: Include targ-vals.h.
 	(sim_engine_run): Change numeric literals to SYS_ constants.
diff --git a/sim/moxie/configure b/sim/moxie/configure
index 5aad79c..d507c4e 100755
--- a/sim/moxie/configure
+++ b/sim/moxie/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2290,6 +2291,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3877,6 +3887,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7304,56 +7349,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11256,7 +11251,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11259 "configure"
+#line 11254 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11362,7 +11357,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11365 "configure"
+#line 11360 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/msp430/ChangeLog b/sim/msp430/ChangeLog
index cdc5cbd..15632ee 100644
--- a/sim/msp430/ChangeLog
+++ b/sim/msp430/ChangeLog
@@ -1,5 +1,9 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* configure.ac: Delete AC_CHECK_HEADERS call.
 	* config.in, configure: Regenerate.
 
diff --git a/sim/msp430/configure b/sim/msp430/configure
index 4488524..461f80a 100755
--- a/sim/msp430/configure
+++ b/sim/msp430/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/or1k/configure b/sim/or1k/configure
index 8887e15..602f66c 100755
--- a/sim/or1k/configure
+++ b/sim/or1k/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2302,6 +2303,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3889,6 +3899,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7316,56 +7361,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11268,7 +11263,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11271 "configure"
+#line 11266 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11374,7 +11369,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11377 "configure"
+#line 11372 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/pru/configure b/sim/pru/configure
index 4488524..461f80a 100755
--- a/sim/pru/configure
+++ b/sim/pru/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/riscv/configure b/sim/riscv/configure
index fca9986..99199aa 100755
--- a/sim/riscv/configure
+++ b/sim/riscv/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2294,6 +2295,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3881,6 +3891,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7308,56 +7353,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11260,7 +11255,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11263 "configure"
+#line 11258 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11366,7 +11361,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11369 "configure"
+#line 11364 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/rl78/ChangeLog b/sim/rl78/ChangeLog
index 4aa6b1f..32cd435 100644
--- a/sim/rl78/ChangeLog
+++ b/sim/rl78/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure.ac: Change AC_CHECK_HEADERS to AC_CHECK_HEADERS_ONCE.
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* configure: Regenerate.
 
 2021-04-02  Mike Frysinger  <vapier@gentoo.org>
diff --git a/sim/rl78/configure b/sim/rl78/configure
index a164b13..8ba5fd0 100755
--- a/sim/rl78/configure
+++ b/sim/rl78/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2282,6 +2283,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -2292,6 +2302,7 @@ as_fn_append ac_func_list " posix_fallocate"
 as_fn_append ac_func_list " sigaction"
 as_fn_append ac_func_list " time"
 as_fn_append ac_func_list " truncate"
+as_fn_append ac_header_list " getopt.h"
 # Check that the precious variables saved in the cache have kept the same
 # value.
 ac_cache_corrupted=false
@@ -3869,6 +3880,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7296,56 +7342,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11248,7 +11244,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11251 "configure"
+#line 11247 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11354,7 +11350,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11357 "configure"
+#line 11353 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11999,17 +11995,8 @@ $as_echo "${WARN_CFLAGS} ${WERROR_CFLAGS}" >&6; }
 fi
 
 
-for ac_header in getopt.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "getopt.h" "ac_cv_header_getopt_h" "$ac_includes_default"
-if test "x$ac_cv_header_getopt_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_GETOPT_H 1
-_ACEOF
 
-fi
 
-done
 
 
 
diff --git a/sim/rl78/configure.ac b/sim/rl78/configure.ac
index 1314b98..fad367c 100644
--- a/sim/rl78/configure.ac
+++ b/sim/rl78/configure.ac
@@ -24,6 +24,6 @@ AC_CONFIG_MACRO_DIRS([../m4 ../.. ../../config])
 SIM_AC_COMMON
 SIM_AC_OPTION_WARNINGS(no)
 
-AC_CHECK_HEADERS(getopt.h)
+AC_CHECK_HEADERS_ONCE(getopt.h)
 
 SIM_AC_OUTPUT
diff --git a/sim/rx/ChangeLog b/sim/rx/ChangeLog
index 6660671..be4c653 100644
--- a/sim/rx/ChangeLog
+++ b/sim/rx/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure.ac: Change AC_CHECK_HEADERS to AC_CHECK_HEADERS_ONCE.
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* Makefile.in (NL_TARGET): Define.
 	(syscalls.o): Delete syscall.h.
 	* syscalls.c: Change syscall.h include to targ-vals.h.
diff --git a/sim/rx/configure b/sim/rx/configure
index 592bd0b..ba9d433 100755
--- a/sim/rx/configure
+++ b/sim/rx/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2287,6 +2288,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -2297,6 +2307,7 @@ as_fn_append ac_func_list " posix_fallocate"
 as_fn_append ac_func_list " sigaction"
 as_fn_append ac_func_list " time"
 as_fn_append ac_func_list " truncate"
+as_fn_append ac_header_list " getopt.h"
 # Check that the precious variables saved in the cache have kept the same
 # value.
 ac_cache_corrupted=false
@@ -3874,6 +3885,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7301,56 +7347,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11253,7 +11249,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11256 "configure"
+#line 11252 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11359,7 +11355,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11362 "configure"
+#line 11358 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11907,17 +11903,8 @@ _ACEOF
 
 
 
-for ac_header in getopt.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "getopt.h" "ac_cv_header_getopt_h" "$ac_includes_default"
-if test "x$ac_cv_header_getopt_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_GETOPT_H 1
-_ACEOF
 
-fi
 
-done
 
 
 # Check whether --enable-cycle-accurate was given.
diff --git a/sim/rx/configure.ac b/sim/rx/configure.ac
index 16e64a5..344ab39 100644
--- a/sim/rx/configure.ac
+++ b/sim/rx/configure.ac
@@ -23,7 +23,7 @@ AC_CONFIG_MACRO_DIRS([../m4 ../.. ../../config])
 
 SIM_AC_COMMON
 
-AC_CHECK_HEADERS(getopt.h)
+AC_CHECK_HEADERS_ONCE(getopt.h)
 
 AC_ARG_ENABLE(cycle-accurate,
 [AS_HELP_STRING([--disable-cycle-accurate],
diff --git a/sim/sh/ChangeLog b/sim/sh/ChangeLog
index 984ff5e..0443ea1 100644
--- a/sim/sh/ChangeLog
+++ b/sim/sh/ChangeLog
@@ -1,5 +1,9 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* Makefile.in (NL_TARGET): Define.
 	* interp.c: Change syscall.h include to targ-vals.h.
 	(trap): Add TARGET_ prefix to all SYS_ constants.
diff --git a/sim/sh/configure b/sim/sh/configure
index f650776..5fac5b8 100755
--- a/sim/sh/configure
+++ b/sim/sh/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2289,6 +2290,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -3876,6 +3886,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7303,56 +7348,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11255,7 +11250,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11258 "configure"
+#line 11253 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11361,7 +11356,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11364 "configure"
+#line 11359 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/sim/v850/ChangeLog b/sim/v850/ChangeLog
index 91741a1..100128f 100644
--- a/sim/v850/ChangeLog
+++ b/sim/v850/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-18  Mike Frysinger  <vapier@gentoo.org>
 
+	* configure.ac: Change AC_CHECK_HEADERS to AC_CHECK_HEADERS_ONCE.
+	* configure: Regenerate.
+
+2021-04-18  Mike Frysinger  <vapier@gentoo.org>
+
 	* configure.ac: Change AC_CHECK_FUNCS to AC_CHECK_FUNCS_ONCE and
 	delete time.
 	* configure: Regenerate.
diff --git a/sim/v850/configure b/sim/v850/configure
index 818ccd2..6dcdb34 100755
--- a/sim/v850/configure
+++ b/sim/v850/configure
@@ -629,6 +629,7 @@ ac_includes_default="\
 # include <unistd.h>
 #endif"
 
+ac_header_list=
 ac_func_list=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
@@ -2295,6 +2296,15 @@ $as_echo "$as_me: creating cache $cache_file" >&6;}
   >$cache_file
 fi
 
+as_fn_append ac_header_list " dlfcn.h"
+as_fn_append ac_header_list " fcntl.h"
+as_fn_append ac_header_list " fpu_control.h"
+as_fn_append ac_header_list " unistd.h"
+as_fn_append ac_header_list " sys/mman.h"
+as_fn_append ac_header_list " sys/resource.h"
+as_fn_append ac_header_list " sys/time.h"
+as_fn_append ac_header_list " sys/times.h"
+as_fn_append ac_header_list " sys/stat.h"
 as_fn_append ac_func_list " __setfpucw"
 as_fn_append ac_func_list " ftruncate"
 as_fn_append ac_func_list " getrusage"
@@ -2311,6 +2321,7 @@ as_fn_append ac_func_list " fork"
 as_fn_append ac_func_list " execve"
 as_fn_append ac_func_list " execv"
 as_fn_append ac_func_list " chown"
+as_fn_append ac_header_list " utime.h"
 # Check that the precious variables saved in the cache have kept the same
 # value.
 ac_cache_corrupted=false
@@ -3888,6 +3899,41 @@ DEPDIR="${am__leading_dot}deps"
 
 
 
+  for ac_header in $ac_header_list
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+
+done
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
   for ac_func in $ac_func_list
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
@@ -7315,56 +7361,6 @@ fi
 
 # Check for common headers.
 # NB: You can assume C11 headers exist.
-for ac_header in unistd.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "unistd.h" "ac_cv_header_unistd_h" "$ac_includes_default"
-if test "x$ac_cv_header_unistd_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UNISTD_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in sys/time.h sys/times.h sys/resource.h sys/mman.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in fcntl.h fpu_control.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
-
-for ac_header in dlfcn.h sys/stat.h
-do :
-  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
-ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
-if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-
-done
 
 
 ac_fn_c_check_member "$LINENO" "struct stat" "st_dev" "ac_cv_member_struct_stat_st_dev" "#ifdef HAVE_SYS_TYPES_H
@@ -11267,7 +11263,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11270 "configure"
+#line 11266 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11373,7 +11369,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11376 "configure"
+#line 11372 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12101,17 +12097,8 @@ fi
 
 
 
-for ac_header in utime.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "utime.h" "ac_cv_header_utime_h" "$ac_includes_default"
-if test "x$ac_cv_header_utime_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_UTIME_H 1
-_ACEOF
 
-fi
 
-done
 
 
 
diff --git a/sim/v850/configure.ac b/sim/v850/configure.ac
index b2f69c3..f2edf1f 100644
--- a/sim/v850/configure.ac
+++ b/sim/v850/configure.ac
@@ -10,6 +10,6 @@ SIM_AC_OPTION_RESERVED_BITS
 SIM_AC_OPTION_BITSIZE(32,31)
 
 AC_CHECK_FUNCS_ONCE(chmod utime fork execve execv chown)
-AC_CHECK_HEADERS(utime.h)
+AC_CHECK_HEADERS_ONCE(utime.h)
 
 SIM_AC_OUTPUT