Linux: Keep termios ioctl constants strictly internal

Undefine TCGETS, TCGETS2, and related ioctl constants in the installed
headers.  Extract the correct constants (using the kernel type
definitions) automatically from the UAPI headers.  The kernel
constants are available under KERNEL_* names during the glibc build,
computed using assembler constant extraction mechanism.

Alpha may have to use TCGETS instead of TCGETS2 because TCTGETS2
became available in Linux 4.20 only.  Introduce ARCH_TCGETS to make
this choice explict.

To support emulation on powerpc, glibc versions of the termios
constants are added to the emulation code in internal-ioctl.h.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

17 files changed, 111 insertions, 260 deletions

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index c47cbdf..0aec783 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -425,6 +425,8 @@ sysdep_headers += \
   bits/termios-tcflow.h \
   # sysdep_headers
 
+gen-as-const-headers += termios-kernel-consts.sym
+
 tests += \
   tst-termios-linux \
   # tests
diff --git a/sysdeps/unix/sysv/linux/alpha/bits/ioctls.h b/sysdeps/unix/sysv/linux/alpha/bits/ioctls.h
deleted file mode 100644
index 77dc0c1..0000000
--- a/sysdeps/unix/sysv/linux/alpha/bits/ioctls.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/* Copyright (C) 1996-2025 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _SYS_IOCTL_H
-# error "Never use <bits/ioctls.h> directly; include <sys/ioctl.h> instead."
-#endif
-
-/* Use the definitions from the kernel header files.  */
-#include <asm/ioctls.h>
-
-/* Oh well, this is necessary since the kernel data structure is
-   different from the user-level version.  */
-#undef  TCGETS
-#undef  TCSETS
-#undef  TCSETSW
-#undef  TCSETSF
-#define TCGETS	_IOR ('t', 19, char[44])
-#define TCSETS	_IOW ('t', 20, char[44])
-#define TCSETSW	_IOW ('t', 21, char[44])
-#define TCSETSF	_IOW ('t', 22, char[44])
-
-#include <linux/sockios.h>
diff --git a/sysdeps/unix/sysv/linux/alpha/termios_arch.h b/sysdeps/unix/sysv/linux/alpha/termios_arch.h
deleted file mode 100644
index 20025f2..0000000
--- a/sysdeps/unix/sysv/linux/alpha/termios_arch.h
+++ /dev/null
@@ -1,26 +0,0 @@
-/* Architectural parameters for Linux termios - Alpha/PowerPC version
-
-   Copyright (C) 1997-2025 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef TERMIOS_INTERNALS_H
-# error "<termios_arch.h> should only be included from <termios_internals.h>"
-#endif
-
-#define _TERMIOS2_NCCS 19
-#define _HAVE_TERMIOS2_C_CC_BEFORE_C_LINE 1
-#define _HAVE_STRUCT_OLD_TERMIOS 0
diff --git a/sysdeps/unix/sysv/linux/bits/ioctls.h b/sysdeps/unix/sysv/linux/bits/ioctls.h
index 1ddcd4f..f340a4f 100644
--- a/sysdeps/unix/sysv/linux/bits/ioctls.h
+++ b/sysdeps/unix/sysv/linux/bits/ioctls.h
@@ -22,4 +22,18 @@
 /* Use the definitions from the kernel header files.  */
 #include <asm/ioctls.h>
 
+/* The GNU C library has a different definition of struct termios,
+   incompatible with what the ioctl interface expects.  The existence
+   of the termios2 ioctls is considered an implementation detail.
+   Undefine all related ioctl constants.  */
+#undef TCGETS
+#undef TCSETS
+#undef TCSETSF
+#undef TCSETSW
+#undef TCGETS2
+#undef TCSETS2
+#undef TCSETSF2
+#undef TCSETSW2
+
+
 #include <linux/sockios.h>
diff --git a/sysdeps/unix/sysv/linux/hppa/bits/ioctls.h b/sysdeps/unix/sysv/linux/hppa/bits/ioctls.h
deleted file mode 100644
index 6563be8..0000000
--- a/sysdeps/unix/sysv/linux/hppa/bits/ioctls.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/* Copyright (C) 1996-2025 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _SYS_IOCTL_H
-# error "Never use <bits/ioctls.h> directly; include <sys/ioctl.h> instead."
-#endif
-
-/* Use the definitions from the kernel header files.  */
-#include <asm/ioctls.h>
-
-/* Oh well, this is necessary since the kernel data structure is
-   different from the user-level version.  */
-#undef  TCGETS
-#undef  TCSETS
-#undef  TCSETSW
-#undef  TCSETSF
-#define TCGETS	_IOR ('T', 16, char[36])
-#define TCSETS	_IOW ('T', 17, char[36])
-#define TCSETSW	_IOW ('T', 18, char[36])
-#define TCSETSF	_IOW ('T', 19, char[36])
-
-#include <linux/sockios.h>
diff --git a/sysdeps/unix/sysv/linux/isatty.c b/sysdeps/unix/sysv/linux/isatty.c
index 3faaec5..e7e98f8 100644
--- a/sysdeps/unix/sysv/linux/isatty.c
+++ b/sysdeps/unix/sysv/linux/isatty.c
@@ -24,6 +24,6 @@ int
 __isatty (int fd)
 {
   struct termios2 k_termios;
-  return INLINE_SYSCALL_CALL (ioctl, fd, TCGETS2, &k_termios) == 0;
+  return INLINE_SYSCALL_CALL (ioctl, fd, ARCH_TCGETS, &k_termios) == 0;
 }
 weak_alias (__isatty, isatty)
diff --git a/sysdeps/unix/sysv/linux/isatty_nostatus.c b/sysdeps/unix/sysv/linux/isatty_nostatus.c
index 406decb..9970442 100644
--- a/sysdeps/unix/sysv/linux/isatty_nostatus.c
+++ b/sysdeps/unix/sysv/linux/isatty_nostatus.c
@@ -22,5 +22,5 @@ int
 __isatty_nostatus (int fd)
 {
   struct termios2 k_termios;
-  return INTERNAL_SYSCALL_CALL (ioctl, fd, TCGETS2, &k_termios) == 0;
+  return INTERNAL_SYSCALL_CALL (ioctl, fd, ARCH_TCGETS, &k_termios) == 0;
 }
diff --git a/sysdeps/unix/sysv/linux/mips/termios_arch.h b/sysdeps/unix/sysv/linux/mips/old_termios.h
index 392d9aa..8164742 100644
--- a/sysdeps/unix/sysv/linux/mips/termios_arch.h
+++ b/sysdeps/unix/sysv/linux/mips/old_termios.h
@@ -1,6 +1,6 @@
-/* Architectural parameters for Linux termios - MIPS version
+/* old_termios.h for MIPS.
 
-   Copyright (C) 1991-2025 Free Software Foundation, Inc.
+   Copyright (C) 2025 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -17,18 +17,15 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#define _TERMIOS2_NCCS 23
-#define _HAVE_TERMIOS2_C_CC_BEFORE_C_LINE 0
-
 #define _HAVE_STRUCT_OLD_TERMIOS 1
 
 #define OLD_NCCS 32
-struct old_termios
+typedef struct old_termios
 {
-  tcflag_t c_iflag;		/* input mode flags */
-  tcflag_t c_oflag;		/* output mode flags */
-  tcflag_t c_cflag;		/* control mode flags */
-  tcflag_t c_lflag;		/* local mode flags */
-  cc_t c_line;			/* line discipline */
-  cc_t c_cc[OLD_NCCS];		/* control characters */
-};
+  tcflag_t c_iflag;             /* input mode flags */
+  tcflag_t c_oflag;             /* output mode flags */
+  tcflag_t c_cflag;             /* control mode flags */
+  tcflag_t c_lflag;             /* local mode flags */
+  cc_t c_line;                  /* line discipline */
+  cc_t c_cc[OLD_NCCS];          /* control characters */
+} old_termios_t;
diff --git a/sysdeps/unix/sysv/linux/powerpc/internal-ioctl.h b/sysdeps/unix/sysv/linux/powerpc/internal-ioctl.h
index 6c21357..94cfd71 100644
--- a/sysdeps/unix/sysv/linux/powerpc/internal-ioctl.h
+++ b/sysdeps/unix/sysv/linux/powerpc/internal-ioctl.h
@@ -1,4 +1,4 @@
-/* Linux internal definitions for ioctl.
+/* Linux internal definitions for ioctl.  powerpc version.
    Copyright (C) 2021-2025 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -17,27 +17,40 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <termios.h>
+#include <termios_internals.h>
+#include <assert.h>
+
+/* PowerPC quirk: on PowerPC only, ioctl() emulates the TCGETS/TCSETS*
+   ioctls with tcgetattr/tcsetattr using the glibc struct termios.
+   As struct termios2 is the same as the kernel struct termios on PowerPC,
+   simply consider the kernel ones as the termios2 interface, even
+   though the kernel doesn't call it that. */
+
+#define GLIBC_TCGETS _IOR ('t', 19, struct termios)
+#define GLIBC_TCSETS _IOW ('t', 20, struct termios)
+#define GLIBC_TCSETSW _IOW ('t', 21, struct termios)
+#define GLIBC_TCSETSF _IOW ('t', 22, struct termios)
 
-/* The user-visible size of struct termios has changed.  Catch ioctl calls
-   using the new-style struct termios, and translate them to old-style.  */
 static inline bool
 __ioctl_arch (int *r, int fd, unsigned long request, void *arg)
 {
+  static_assert (GLIBC_TCGETS != KERNEL_TCGETS2,
+                 "emulation not possible due to matching ioctl constants");
   switch (request)
     {
-    case TCGETS:
+    case GLIBC_TCGETS:
       *r = __tcgetattr (fd, (struct termios *) arg);
       break;
 
-    case TCSETS:
+    case GLIBC_TCSETS:
       *r = __tcsetattr (fd, TCSANOW, (struct termios *) arg);
       break;
 
-    case TCSETSW:
+    case GLIBC_TCSETSW:
       *r = __tcsetattr (fd, TCSADRAIN, (struct termios *) arg);
       break;
 
-    case TCSETSF:
+    case GLIBC_TCSETSF:
       *r = __tcsetattr (fd, TCSAFLUSH, (struct termios *) arg);
       break;
 
diff --git a/sysdeps/unix/sysv/linux/powerpc/termios_arch.h b/sysdeps/unix/sysv/linux/powerpc/termios_arch.h
deleted file mode 100644
index 919b437..0000000
--- a/sysdeps/unix/sysv/linux/powerpc/termios_arch.h
+++ /dev/null
@@ -1,33 +0,0 @@
-/* Architectural parameters for Linux termios - PowerPC version
-
-   Copyright (C) 1997-2025 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define _TERMIOS2_NCCS 19
-#define _HAVE_TERMIOS2_C_CC_BEFORE_C_LINE 1
-#define _HAVE_STRUCT_OLD_TERMIOS 0
-
-/* PowerPC quirk: on PowerPC only, ioctl() emulates the TCGETS/TCSETS*
-   ioctls with tcgetattr/tcsetattr using the glibc struct termios.
-   As struct termios2 is the same as the kernel struct termios on PowerPC,
-   simply consider the kernel ones as the termios2 interface, even
-   though the kernel doesn't call it that. */
-
-#define TCGETS2	 _IOR ('t', 19, struct termios2)
-#define TCSETS2	 _IOW ('t', 20, struct termios2)
-#define TCSETSW2 _IOW ('t', 21, struct termios2)
-#define TCSETSF2 _IOW ('t', 22, struct termios2)
diff --git a/sysdeps/unix/sysv/linux/sparc/bits/ioctls.h b/sysdeps/unix/sysv/linux/sparc/bits/ioctls.h
deleted file mode 100644
index 1a95466..0000000
--- a/sysdeps/unix/sysv/linux/sparc/bits/ioctls.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/* Copyright (C) 1996-2025 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _SYS_IOCTL_H
-# error "Never use <bits/ioctls.h> directly; include <sys/ioctl.h> instead."
-#endif
-
-/* Use the definitions from the kernel header files.  */
-#include <asm/ioctls.h>
-
-/* Oh well, this is necessary since the kernel data structure is
-   different from the user-level version.  */
-#undef  TCGETS
-#undef  TCSETS
-#undef  TCSETSW
-#undef  TCSETSF
-#define TCGETS	_IOR ('T', 8, char[36])
-#define TCSETS	_IOW ('T', 9, char[36])
-#define TCSETSW	_IOW ('T', 10, char[36])
-#define TCSETSF	_IOW ('T', 11, char[36])
-
-#include <linux/sockios.h>
diff --git a/sysdeps/unix/sysv/linux/sparc/termios_arch.h b/sysdeps/unix/sysv/linux/sparc/old_termios.h
index f3b3f65..d7af589 100644
--- a/sysdeps/unix/sysv/linux/sparc/termios_arch.h
+++ b/sysdeps/unix/sysv/linux/sparc/old_termios.h
@@ -1,6 +1,6 @@
-/* Architectural parameters for Linux termios - SPARC version
+/* old_termios.h for SPARC.
 
-   Copyright (C) 1991-2025 Free Software Foundation, Inc.
+   Copyright (C) 2025 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -17,18 +17,15 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#define _TERMIOS2_NCCS 19
-#define _HAVE_TERMIOS2_C_CC_BEFORE_C_LINE 0
-
 #define _HAVE_STRUCT_OLD_TERMIOS 1
 
 #define OLD_NCCS 17
-struct old_termios
+typedef struct old_termios
 {
-  tcflag_t c_iflag;		/* input mode flags */
-  tcflag_t c_oflag;		/* output mode flags */
-  tcflag_t c_cflag;		/* control mode flags */
-  tcflag_t c_lflag;		/* local mode flags */
-  cc_t c_line;			/* line discipline */
-  cc_t c_cc[OLD_NCCS];		/* control characters */
-};
+  tcflag_t c_iflag;             /* input mode flags */
+  tcflag_t c_oflag;             /* output mode flags */
+  tcflag_t c_cflag;             /* control mode flags */
+  tcflag_t c_lflag;             /* local mode flags */
+  cc_t c_line;                  /* line discipline */
+  cc_t c_cc[OLD_NCCS];          /* control characters */
+} old_termios_t;
diff --git a/sysdeps/unix/sysv/linux/tcgetattr.c b/sysdeps/unix/sysv/linux/tcgetattr.c
index ca17569..36f68a7 100644
--- a/sysdeps/unix/sysv/linux/tcgetattr.c
+++ b/sysdeps/unix/sysv/linux/tcgetattr.c
@@ -22,7 +22,7 @@ int
 __tcgetattr (int fd, struct termios *termios_p)
 {
   struct termios2 k_termios;
-  long int retval = INLINE_SYSCALL_CALL (ioctl, fd, TCGETS2, &k_termios);
+  long int retval = INLINE_SYSCALL_CALL (ioctl, fd, ARCH_TCGETS, &k_termios);
 
   if (__glibc_likely (retval != -1))
     {
diff --git a/sysdeps/unix/sysv/linux/tcsetattr.c b/sysdeps/unix/sysv/linux/tcsetattr.c
index 4f07a03..ad8f2df 100644
--- a/sysdeps/unix/sysv/linux/tcsetattr.c
+++ b/sysdeps/unix/sysv/linux/tcsetattr.c
@@ -19,6 +19,12 @@
 
 #define static_assert_equal(x,y) _Static_assert ((x) == (y), #x " != " #y)
 
+static_assert_equal (sizeof (struct termios2), KERNEL_TERMIOS2_SIZE);
+static_assert_equal (offsetof (struct termios2, c_cc),
+                     KERNEL_TERMIOS2_CC_OFFSET);
+static_assert_equal (offsetof (struct termios2, c_line),
+                     KERNEL_TERMIOS2_LINE_OFFSET);
+
 /* Set the state of FD to *TERMIOS_P.  */
 int
 __tcsetattr (int fd, int optional_actions, const struct termios *termios_p)
@@ -53,10 +59,10 @@ __tcsetattr (int fd, int optional_actions, const struct termios *termios_p)
    */
   static_assert_equal(TCSADRAIN, TCSANOW + 1);
   static_assert_equal(TCSAFLUSH, TCSANOW + 2);
-  static_assert_equal(TCSETSW2,  TCSETS2 + 1);
-  static_assert_equal(TCSETSF2,  TCSETS2 + 2);
-  static_assert_equal(TCSETSW,   TCSETS  + 1);
-  static_assert_equal(TCSETSF,   TCSETS  + 2);
+  static_assert_equal(KERNEL_TCSETSW2, KERNEL_TCSETS2 + 1);
+  static_assert_equal(KERNEL_TCSETSF2, KERNEL_TCSETS2 + 2);
+  static_assert_equal(KERNEL_TCSETSW,  KERNEL_TCSETS  + 1);
+  static_assert_equal(KERNEL_TCSETSF,  KERNEL_TCSETS  + 2);
 
   cmd = (long)optional_actions - TCSANOW;
   if (cmd > 2)
@@ -66,11 +72,11 @@ __tcsetattr (int fd, int optional_actions, const struct termios *termios_p)
       k_termios.c_ospeed != k_termios.c_ispeed ||
       cbaud (k_termios.c_cflag) == __BOTHER)
     {
-      cmd += TCSETS2;
+      cmd += KERNEL_TCSETS2;
     }
   else
     {
-      cmd += TCSETS;
+      cmd += KERNEL_TCSETS;
       k_termios.c_cflag &= ~CIBAUD;
     }
 
diff --git a/sysdeps/unix/sysv/linux/termios-kernel-consts.sym b/sysdeps/unix/sysv/linux/termios-kernel-consts.sym
new file mode 100644
index 0000000..3856a8c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/termios-kernel-consts.sym
@@ -0,0 +1,26 @@
+#include <linux/termios.h>
+#include <stddef.h>
+
+#ifdef TCGETS2
+# define STRUCT_TERMIOS struct termios2
+#else
+# define TCGETS2  TCGETS
+# define TCSETS2  TCSETS
+# define TCSETSW2 TCSETSW
+# define TCSETSF2 TCSETSF
+# define STRUCT_TERMIOS struct termios
+#endif
+
+--
+KERNEL_TCGETS TCGETS
+KERNEL_TCSETS TCSETS
+KERNEL_TCSETSF TCSETSF
+KERNEL_TCSETSW TCSETSW
+KERNEL_TCGETS2 TCGETS2
+KERNEL_TCSETS2 TCSETS2
+KERNEL_TCSETSF2 TCSETSF2
+KERNEL_TCSETSW2 TCSETSW2
+KERNEL_TERMIOS2_SIZE sizeof (STRUCT_TERMIOS)
+KERNEL_TERMIOS2_CC_OFFSET offsetof (STRUCT_TERMIOS, c_cc)
+KERNEL_TERMIOS2_LINE_OFFSET offsetof (STRUCT_TERMIOS, c_line)
+_TERMIOS2_NCCS sizeof ((STRUCT_TERMIOS) { 0 }.c_cc) / sizeof (cc_t)
diff --git a/sysdeps/unix/sysv/linux/termios_arch.h b/sysdeps/unix/sysv/linux/termios_arch.h
deleted file mode 100644
index 8dbf420..0000000
--- a/sysdeps/unix/sysv/linux/termios_arch.h
+++ /dev/null
@@ -1,23 +0,0 @@
-/* Architectural parameters for Linux termios - generic version
-
-   Copyright (C) 1997-2025 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define _TERMIOS2_NCCS 19
-#define _HAVE_TERMIOS2_C_CC_BEFORE_C_LINE 0
-
-#define _HAVE_STRUCT_OLD_TERMIOS 0
diff --git a/sysdeps/unix/sysv/linux/termios_internals.h b/sysdeps/unix/sysv/linux/termios_internals.h
index e8dbfe7..b2f3f1b 100644
--- a/sysdeps/unix/sysv/linux/termios_internals.h
+++ b/sysdeps/unix/sysv/linux/termios_internals.h
@@ -30,7 +30,18 @@
 #include <sysdep.h>
 #include <shlib-compat.h>
 
-#include <termios_arch.h>
+#include <termios-kernel-consts.h>
+
+/* Alpha got termios2 late, but TCGETS has exactly the same structure
+   format and function as TCGETS2. On all other platforms, the termios2
+   interface exists as far back as this version of glibc supports.
+
+   For TCSETS* it is more complicated; this is handled in tcsetattr.c.  */
+#ifdef __ASSUME_TERMIOS2
+# define ARCH_TCGETS KERNEL_TCGETS2
+#else
+# define ARCH_TCGETS KERNEL_TCGETS
+#endif
 
 /* ---- Kernel interface definitions ---- */
 
@@ -44,7 +55,7 @@ struct termios2
   tcflag_t c_oflag;		/* output mode flags */
   tcflag_t c_cflag;		/* control mode flags */
   tcflag_t c_lflag;		/* local mode flags */
-#if _HAVE_TERMIOS2_C_CC_BEFORE_C_LINE
+#if KERNEL_TERMIOS2_CC_OFFSET < KERNEL_TERMIOS2_LINE_OFFSET
   cc_t c_cc[_TERMIOS2_NCCS];	/* control characters */
   cc_t c_line;			/* line discipline */
 #else
@@ -55,26 +66,6 @@ struct termios2
   speed_t c_ospeed;		/* output speed */
 };
 
-/* Alpha got termios2 late, but TCGETS has exactly the same structure
-   format and function as TCGETS2. On all other platforms, the termios2
-   interface exists as far back as this version of glibc supports.
-
-   For TCSETS* it is more complicated; this is handled in tcsetattr.c.
-
-   Some other architectures only have the equivalent of the termios2
-   interface, in which case the old ioctl names are the only ones
-   presented, but are equivalent to the new ones. */
-#ifndef TCGETS2
-# define TCGETS2  TCGETS
-# define TCSETS2  TCSETS
-# define TCSETSW2 TCSETSW
-# define TCSETSF2 TCSETSF
-#elif !__ASSUME_TERMIOS2
-/* Hack for Alpha */
-# undef  TCGETS2
-# define TCGETS2 TCGETS
-#endif
-
 /* ---- Application interface definitions ---- */
 
 /*
@@ -91,12 +82,7 @@ struct termios2
  * This only applies to SPARC and MIPS; for other architectures the
  * new and old speed_t interfaces both use the same struct termios.
  */
-#if _HAVE_STRUCT_OLD_TERMIOS
-typedef struct old_termios old_termios_t;
-#else
-# define OLD_NCCS NCCS
-typedef struct termios old_termios_t;
-#endif
+#include <old_termios.h>
 
 /* ---- Internal function definitions ---- */