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authorUlrich Drepper <drepper@redhat.com>1998-06-29 12:44:22 +0000
committerUlrich Drepper <drepper@redhat.com>1998-06-29 12:44:22 +0000
commitfdacb17d4819c7112a147195c5ce3c82147f4b46 (patch)
treed1c400488d3bc8dfe707645a0fc38916e223614c /FAQ
parentba488034eabd1affd6b4b3e8838abde0f4d0504e (diff)
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Update.
1998-06-29 12:27 Ulrich Drepper <drepper@cygnus.com> * argp/argp.h: Use __PMT instead of __P for function pointer. * iconv/gconv.h: Likewise. * io/fts.h: Likewise. * io/ftw.h: Likewise. * libio/libio.h: Likewise. * malloc/mcheck.h: Likewise. * misc/search.h: Likewise. * posix/glob.h: Likewise. * resolv/resolv.h: Likewise. * signal/signal.h: Likewise. * stdlib/stdlib.h: Likewise. * sysdeps/unix/sysv/linux/bits/sigaction.h: Likewise. * sysdeps/unix/sysv/linux/bits/siginfo.h: Likewise. 1998-06-26 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * Makeconfig (CPPFLAGS): Use $($(subdir)-CPPFLAGS) only once. 1998-06-27 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * posix/wordexp.c (parse_param): Fix memory leak. 1998-06-27 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * libc.map: Export _IO_ftrylockfile. 1998-06-27 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * sysdeps/unix/sysv/linux/aio_sigqueue.c: Use get[pu]id instead of __get[pu]id. 1998-06-28 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * elf/dl-misc.c (_dl_debug_message): Don't cache the pid. * elf/dl-runtime.c (_dl_object_relocation_scope): Avoid adding the same search list twice. 1998-06-29 Andreas Jaeger <aj@arthur.rhein-neckar.de> * login/programs/utmpd.c (handle_requests): Set and use maximal fd used to optimize loop/select. 1998-06-24 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * sysdeps/generic/init-first.c: Don't define __libc_pid. * sysdeps/unix/sysv/linux/init-first.c: Likewise. * sysdeps/mach/hurd/i386/init-first.c: Likewise. * sysdeps/mach/hurd/mips/init-first.c: Likewise. * sysdeps/arm/init-first.c: Likewise. * posix/getopt_init.c: Don't use __libc_pid. * sysdeps/unix/sysv/linux/aio_sigqueue.c: Likewise. * sysdeps/unix/sysv/linux/sigqueue.c: Likewise. * libc.map: Remove __libc_uid and __libc_pid.
Diffstat (limited to 'FAQ')
-rw-r--r--FAQ73
1 files changed, 62 insertions, 11 deletions
diff --git a/FAQ b/FAQ
index f1ba410..b89dd91 100644
--- a/FAQ
+++ b/FAQ
@@ -5,7 +5,7 @@ and using glibc. Please make sure you read this before sending questions or
bug reports to the maintainers.
The GNU C library is very complex. The installation process has not been
-completely automated; there are too many variables. You can do substantial
+completely automated; there are too many variables. You can do substantial
damage to your system by installing the library incorrectly. Make sure you
understand what you are undertaking before you begin.
@@ -85,6 +85,8 @@ please let me know.
2.20. What do I need for C++ development?
2.21. Even statically linked programs need some shared libraries
which is not acceptable for me. What can I do?
+2.22. I just upgraded my Linux system to glibc and now I get
+ errors whenever I try to link any program.
3. Source and binary incompatibilities, and what to do about them
@@ -123,6 +125,7 @@ please let me know.
4.3. When I set the timezone by setting the TZ environment variable
to EST5EDT things go wrong since glibc computes the wrong time
from this information.
+4.4. What other sources of documentation about glibc are available?
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
@@ -376,10 +379,10 @@ any other link path.
1.14. What's the problem with configure --enable-omitfp?
{AJ} When --enable-omitfp is set the libraries are built without frame
-pointers. Some compilers produce buggy code for this model and therefore we
+pointers. Some compilers produce buggy code for this model and therefore we
don't advise using it at the moment.
-If you use --enable-omitfp, you're on your own. If you encounter problems
+If you use --enable-omitfp, you're on your own. If you encounter problems
with a library that was build this way, we advise you to rebuild the library
without --enable-omitfp. If the problem vanishes consider tracking the
problem down and report it as compiler failure.
@@ -802,6 +805,25 @@ option is using NSS. There is no switch anymore. Therefore it is
*highly* recommended *not* to use --enable-static-nss since this makes
the behaviour of the programs on the system inconsistent.
+
+2.22. I just upgraded my Linux system to glibc and now I get
+ errors whenever I try to link any program.
+
+{ZW} This happens when you have installed glibc as the primary C library but
+have stray symbolic links pointing at your old C library. If the first
+`libc.so' the linker finds is libc 5, it will use that. Your program
+expects to be linked with glibc, so the link fails.
+
+The most common case is that glibc put its `libc.so' in /usr/lib, but there
+was a `libc.so' from libc 5 in /lib, which gets searched first. To fix the
+problem, just delete /lib/libc.so. You may also need to delete other
+symbolic links in /lib, such as /lib/libm.so if it points to libm.so.5.
+
+{AJ} The perl script test-installation.pl which is run as last step during
+an installation of glibc that is configured with --prefix=/usr should help
+detect these situations. If the script reports problems, something is
+really screwed up.
+
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
@@ -995,11 +1017,11 @@ siginterrupt().
functions. Why?
{AJ} glibc 2.1 has special string functions that are faster than the normal
-library functions. Some of the functions are additionally implemented as
+library functions. Some of the functions are additionally implemented as
inline functions and others as macros.
The optimized string functions are only used when compiling with
-optimizations (-O1 or higher). The behavior can be changed with two feature
+optimizations (-O1 or higher). The behavior can be changed with two feature
macros:
* __NO_STRING_INLINES: Don't do any string optimizations.
@@ -1008,7 +1030,7 @@ macros:
Since some of these string functions are now additionally defined as macros,
code like "char *strncpy();" doesn't work anymore (and is unnecessary, since
-<string.h> has the necessary declarations). Either change your code or
+<string.h> has the necessary declarations). Either change your code or
define __NO_STRING_INLINES.
{UD} Another problem in this area is that gcc still has problems on machines
@@ -1033,22 +1055,37 @@ This disables the optimization for that specific call.
{RM,AJ} Constructs like:
static FILE *InPtr = stdin;
-lead to this message. This is correct behaviour with glibc since stdin is
-not a constant expression. Please note that a strict reading of ISO C does
+lead to this message. This is correct behaviour with glibc since stdin is
+not a constant expression. Please note that a strict reading of ISO C does
not allow above constructs.
One of the advantages of this is that you can assign to stdin, stdout, and
stderr just like any other global variable (e.g. `stdout = my_stream;'),
which can be very useful with custom streams that you can write with libio
-(but beware this is not necessarily portable). The reason to implement it
+(but beware this is not necessarily portable). The reason to implement it
this way were versioning problems with the size of the FILE structure.
+To fix those programs you've got to initialize the variable at run time.
+This can be done, e.g. in main, like:
+
+static FILE *InPtr;
+int main(void)
+{
+ InPtr = stdin;
+}
+
+or by constructors (beware this is gcc specific):
+
+static FILE *InPtr;
+static void inPtr_construct (void) __attribute__((constructor));
+static void inPtr_construct (void) { InPtr = stdin; }
+
3.10. I can't compile with gcc -traditional (or
-traditional-cpp). Why?
{AJ} glibc2 does break -traditional and -traditonal-cpp - and will continue
-to do so. For example constructs of the form:
+to do so. For example constructs of the form:
enum {foo
#define foo foo
@@ -1063,7 +1100,7 @@ check with #ifdef).
{AJ} The GNU C library is compatible with the ANSI/ISO C standard. If
you're using `gcc -ansi', the glibc includes which are specified in the
-standard follow the standard. The ANSI/ISO C standard defines what has to be
+standard follow the standard. The ANSI/ISO C standard defines what has to be
in the include files - and also states that nothing else should be in the
include files (btw. you can still enable additional standards with feature
flags).
@@ -1134,6 +1171,20 @@ So, please avoid sending bug reports about time related problems if you use
the POSIX method and you have not verified something is really broken by
reading the POSIX standards.
+
+4.4. What other sources of documentation about glibc are available?
+
+{AJ} The FSF has a page about the GNU C library at
+<http://www.gnu.org/software/libc/>. The problem data base of open and
+solved bugs in GNU libc is available at
+<http://www-gnats.gnu.org:8080/cgi-bin/wwwgnats.pl>. Eric Green has written
+a HowTo for converting from Linux libc5 to glibc2. The HowTo is accessable
+via the FSF page and at <http://www.imaxx.net/~thrytis/glibc>. Frodo
+Looijaard describes a different way installing glibc2 as secondary libc at
+<http://huizen.dds.nl/~frodol/glibc>.
+
+Please note that this is not a complete list.
+
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~