glibc/sysdeps/unix/sysv/linux/configure
Joseph Myers 5b4ecd3f95 Require Linux 3.2 except on x86 / x86_64, 3.2 headers everywhere.
In <https://sourceware.org/ml/libc-alpha/2016-01/msg00885.html> I
proposed a minimum Linux kernel version of 3.2 for glibc 2.24, since
Linux 2.6.32 has reached EOL.

In the discussion in February, some concerns were expressed about
compatibility with OpenVZ containers.  It's not clear that these are
real issues, given OpenVZ backporting kernel features and faking the
kernel version for guest software, as discussed in
<https://sourceware.org/ml/libc-alpha/2016-02/msg00278.html>.  It's
also not clear that supporting running GNU/Linux distributions from
late 2016 (at the earliest) on a kernel series from 2009 is a sensible
expectation.  However, as an interim step, this patch increases the
requirement everywhere except x86 / x86_64 (since the controversy was
only about those architectures); the special caveats and settings can
easily be removed later when we're ready to increase the requirements
on x86 / x86_64 (and if someone would like to raise the issue on LWN
as suggested in the previous discussion, that would be welcome).  3.2
kernel headers are required everywhere by this patch.

(x32 already requires 3.4 or later, so is unaffected by this patch.)

As usual for such a change, this patch only changes the configure
scripts and associated documentation.  The intent is to follow up with
removal of dead __LINUX_KERNEL_VERSION conditionals.  Each __ASSUME_*
or other macro that becomes dead can then be removed independently.

Tested for x86_64 and x86.

	* sysdeps/unix/sysv/linux/configure.ac (LIBC_LINUX_VERSION):
	Define to 3.2.0.
	(arch_minimum_kernel): Likewise.
	* sysdeps/unix/sysv/linux/configure: Regenerated.
	* sysdeps/unix/sysv/linux/i386/configure.ac (arch_minimum_kernel):
	Define to 2.6.32.
	* sysdeps/unix/sysv/linux/i386/configure: Regenerated.
	* sysdeps/unix/sysv/linux/x86_64/64/configure.ac
	(arch_minimum_kernel): Define to 2.6.32.
	* sysdeps/unix/sysv/linux/x86_64/64/configure: Regenerated.
	* README: Document Linux 3.2 requirement.
	* manual/install.texi (Linux): Document Linux 3.2 headers
	requirement.
	* INSTALL: Regenerated.
2016-02-24 17:15:12 +00:00

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# ac_fn_c_check_header_compile LINENO HEADER VAR INCLUDES
# -------------------------------------------------------
# Tests whether HEADER exists and can be compiled using the include files in
# INCLUDES, setting the cache variable VAR accordingly.
ac_fn_c_check_header_compile ()
{
as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $2" >&5
$as_echo_n "checking for $2... " >&6; }
if eval \${$3+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$4
#include <$2>
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
eval "$3=yes"
else
eval "$3=no"
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
eval ac_res=\$$3
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
$as_echo "$ac_res" >&6; }
eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
} # ac_fn_c_check_header_compile
# This file is generated from configure.ac by Autoconf. DO NOT EDIT!
# Local configure fragment for sysdeps/unix/sysv/linux.
if test -n "$sysheaders"; then
OLD_CPPFLAGS=$CPPFLAGS
CPPFLAGS="$CPPFLAGS $SYSINCLUDES"
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking installed Linux kernel header files" >&5
$as_echo_n "checking installed Linux kernel header files... " >&6; }
if ${libc_cv_linux320+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <linux/version.h>
#if !defined LINUX_VERSION_CODE || LINUX_VERSION_CODE < (3 *65536+ 2 *256+ 0) /* 3.2.0 */
# error kernel headers missing or too old
#endif
int
main ()
{
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
libc_cv_linux320='3.2.0 or later'
else
libc_cv_linux320='missing or too old!'
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_linux320" >&5
$as_echo "$libc_cv_linux320" >&6; }
if test "$libc_cv_linux320" != '3.2.0 or later'; then
as_fn_error $? "GNU libc requires kernel header files from
Linux 3.2.0 or later to be installed before configuring.
The kernel header files are found usually in /usr/include/asm and
/usr/include/linux; make sure these directories use files from
Linux 3.2.0 or later. This check uses <linux/version.h>, so
make sure that file was built correctly when installing the kernel header
files. To use kernel headers not from /usr/include/linux, use the
configure option --with-headers." "$LINENO" 5
fi
# If the user gave a minimal version number test whether the available
# kernel headers are young enough. Additionally we have minimal
# kernel versions for some architectures. If a previous configure fragment
# set arch_minimum_kernel already, let that override our defaults here.
# Note that we presume such a fragment has set libc_cv_gcc_unwind_find_fde
# if appropriate too.
test -n "$arch_minimum_kernel" || arch_minimum_kernel=3.2.0
if test -n "$minimum_kernel"; then
user_version=$((`echo "$minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/\1 \* 65536 + \2 \* 256 + \3/'`))
arch_version=$((`echo "$arch_minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/\1 \* 65536 + \2 \* 256 + \3/'`))
if test $user_version -lt $arch_version; then
{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: minimum kernel version reset to $arch_minimum_kernel" >&5
$as_echo "$as_me: WARNING: minimum kernel version reset to $arch_minimum_kernel" >&2;}
minimum_kernel=$arch_minimum_kernel
fi
else
minimum_kernel=$arch_minimum_kernel
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for kernel header at least $minimum_kernel" >&5
$as_echo_n "checking for kernel header at least $minimum_kernel... " >&6; }
decnum=`echo "$minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/(\1 * 65536 + \2 * 256 + \3)/'`;
abinum=`echo "$minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/\1,\2,\3/'`;
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <linux/version.h>
#if LINUX_VERSION_CODE < $decnum
# error kernel headers too old
#endif
int
main ()
{
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
libc_minimum_kernel=ok
else
libc_minimum_kernel='too old!'
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_minimum_kernel" >&5
$as_echo "$libc_minimum_kernel" >&6; }
if test "$libc_minimum_kernel" = ok; then
cat >>confdefs.h <<_ACEOF
#define __LINUX_KERNEL_VERSION $decnum
_ACEOF
cat >>confdefs.h <<_ACEOF
#define __ABI_TAG_VERSION $abinum
_ACEOF
else
as_fn_error $? "*** The available kernel headers are older than the requested
*** compatible kernel version" "$LINENO" 5
fi
# Until we start requiring 2.6.37+ headers, we need to check for the
# availability of linux/fanotify.h for testing purposes.
ac_fn_c_check_header_compile "$LINENO" "linux/fanotify.h" "ac_cv_header_linux_fanotify_h" "/* No default includes. */
"
if test "x$ac_cv_header_linux_fanotify_h" = xyes; then :
$as_echo "#define HAVE_LINUX_FANOTIFY_H 1" >>confdefs.h
fi
if test -n "$sysheaders"; then
CPPFLAGS=$OLD_CPPFLAGS
fi
if test "$prefix" = "/usr/local" -o "$prefix" = "/usr/local/" -o "$prefix" = "NONE"; then
if test $enable_sanity = yes; then
echo "\
*** On GNU/Linux systems the GNU C Library should not be installed into
*** /usr/local since this might make your system totally unusable.
*** We strongly advise to use a different prefix. For details read the FAQ.
*** If you really mean to do this, run configure again using the extra
*** parameter \`--disable-sanity-checks'."
exit 1
else
echo "\
*** WARNING: Do you really want to install the GNU C Library into /usr/local?
*** This might make your system totally unusable, for details read the FAQ."
fi
fi
# One Linux we use ldconfig.
use_ldconfig=yes
if test $host = $build; then
# If $prefix/include/{net,scsi} are symlinks, make install will
# clobber what they're linked to (probably a kernel tree).
# test -L ought to work on all Linux boxes.
if test "x$prefix" != xNONE; then
ac_prefix=$prefix
else
ac_prefix=$ac_default_prefix
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for symlinks in ${ac_prefix}/include" >&5
$as_echo_n "checking for symlinks in ${ac_prefix}/include... " >&6; }
ac_message=
if test -L ${ac_prefix}/include/net; then
ac_message="$ac_message
${ac_prefix}/include/net is a symlink"
fi
if test -L ${ac_prefix}/include/scsi; then
ac_message="$ac_message
${ac_prefix}/include/scsi is a symlink"
fi
if test -n "$ac_message"; then
as_fn_error $? "$ac_message
\`make install' will destroy the target of the link(s).
Delete the links and re-run configure, or better still, move the entire
${ac_prefix}/include directory out of the way." "$LINENO" 5
else
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: ok" >&5
$as_echo "ok" >&6; }
fi
fi
# We have inlined syscalls.
$as_echo "#define HAVE_INLINED_SYSCALLS 1" >>confdefs.h