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view m4/double-slash-root.m4 @ 17627:4d899884c95c
m4: fix gl_TIMER_TIME() detection of threads on uClibc
The timer_time.m4 gl_TIMER_TIME function determines which libraries
need to be linked to get access to the timer function, generally -lrt
for Linux systems. On platforms where threads are used, librt
typically uses thread functions from libpthread.
However, the test to determine whether the platform has thread or not
is incorrect: it assumes that if the C library is uClibc, then threads
are not available. This is actually not true: uClibc has configurable
thread support, and when thread support is available, librt calls
libpthread functions.
This is important when static linking is used, because otherwise only
-lrt is used at link time, which fails because librt calls undefined
thread functions. Both -lrt and -lpthread must be passed.
This problem is fixed by making the uClibc thread detection a bit
smarter, thanks to the usage of the __HAS_NO_THREADS__ macro defined
in <bits/uClibc_config.h>, which itself is included by <features.h>.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
| author | Thomas Petazzoni <thomas.petazzoni@free-electrons.com> |
|---|---|
| date | Sat, 22 Feb 2014 00:41:38 +0100 |
| parents | 344018b6e5d7 |
| children |
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# double-slash-root.m4 serial 4 -*- Autoconf -*- dnl Copyright (C) 2006, 2008-2014 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. AC_DEFUN([gl_DOUBLE_SLASH_ROOT], [ AC_REQUIRE([AC_CANONICAL_HOST]) AC_CACHE_CHECK([whether // is distinct from /], [gl_cv_double_slash_root], [ if test x"$cross_compiling" = xyes ; then # When cross-compiling, there is no way to tell whether // is special # short of a list of hosts. However, the only known hosts to date # that have a distinct // are Apollo DomainOS (too old to port to), # Cygwin, and z/OS. If anyone knows of another system for which // has # special semantics and is distinct from /, please report it to # <bug-gnulib@gnu.org>. case $host in *-cygwin | i370-ibm-openedition) gl_cv_double_slash_root=yes ;; *) # Be optimistic and assume that / and // are the same when we # don't know. gl_cv_double_slash_root='unknown, assuming no' ;; esac else set x `ls -di / // 2>/dev/null` if test "$[2]" = "$[4]" && wc //dev/null >/dev/null 2>&1; then gl_cv_double_slash_root=no else gl_cv_double_slash_root=yes fi fi]) if test "$gl_cv_double_slash_root" = yes; then AC_DEFINE([DOUBLE_SLASH_IS_DISTINCT_ROOT], [1], [Define to 1 if // is a file system root distinct from /.]) fi ])