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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.
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Joseph Myers
Joseph Myers committed Feb 24, 2016
1 parent 8dfdd07 commit 5b4ecd3f95695ef593e4474b4ab5a117291ba5fc
@@ -1,3 +1,20 @@
2016-02-24 Joseph Myers <joseph@codesourcery.com>

* 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 Andreas Schwab <schwab@suse.de>

* math/test-math-isinff.cc (do_test): Only call isinfl and isnanl
@@ -426,7 +426,7 @@ Specific advice for GNU/Linux systems
=====================================

If you are installing the GNU C Library on GNU/Linux systems, you need
to have the header files from a 2.6.32 or newer kernel around for
to have the header files from a 3.2 or newer kernel around for
reference. These headers must be installed using 'make
headers_install'; the headers present in the kernel source directory are
not suitable for direct use by the GNU C Library. You do not need to
7 NEWS
@@ -7,6 +7,13 @@ using `glibc' in the "product" field.

Version 2.24

* The minimum Linux kernel version that this version of the GNU C Library
can be used with is 3.2, except on i[4567]86 and x86_64, where Linux
kernel version 2.6.32 or later suffices (on architectures that already
required kernel versions more recent than 3.2, those requirements remain
unchanged). Linux 3.2 or later kernel headers are required on all
architectures.

* The pap_AN locale has been deleted. This has been deprecated for a long
time. It has been replaced by pap_AW & pap_CW, both of which have long
been included in previous releases.
4 README
@@ -17,7 +17,9 @@ GNU/Hurd support requires out-of-tree patches that will eventually be
incorporated into an official GNU C Library release.

When working with Linux kernels, this version of the GNU C Library
requires Linux kernel version 2.6.32 or later.
requires Linux kernel version 3.2 or later on all architectures except
i[4567]86 and x86_64, where Linux kernel version 2.6.32 or later
suffices.

Also note that the shared version of the libgcc_s library must be
installed for the pthread library to work correctly.
@@ -489,7 +489,7 @@ patches, although we try to avoid this.
@cindex kernel header files

If you are installing @theglibc{} on @gnulinuxsystems{}, you need to have
the header files from a 2.6.32 or newer kernel around for reference.
the header files from a 3.2 or newer kernel around for reference.
These headers must be installed using @samp{make headers_install}; the
headers present in the kernel source directory are not suitable for
direct use by @theglibc{}. You do not need to use that kernel, just have
@@ -39,13 +39,13 @@ 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_linux2632+:} false; then :
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 < (2 *65536+ 6 *256+ 32) /* 2.6.32 */
#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
@@ -57,20 +57,20 @@ main ()
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
libc_cv_linux2632='2.6.32 or later'
libc_cv_linux320='3.2.0 or later'
else
libc_cv_linux2632='missing or too old!'
libc_cv_linux320='missing or too old!'
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_linux2632" >&5
$as_echo "$libc_cv_linux2632" >&6; }
if test "$libc_cv_linux2632" != '2.6.32 or later'; then
{ $as_echo "$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 $? "GNU libc requires kernel header files from
Linux 2.6.32 or later to be installed before configuring.
Linux 3.2.0 or later to be installed before configuring.
The kernel header files are found usually in /usr/include/asm and
/usr/include/linux; make sure these directories use files from
Linux 2.6.32 or later. This check uses <linux/version.h>, so
Linux 3.2.0 or later. This check uses <linux/version.h>, so
make sure that file was built correctly when installing the kernel header
files. To use kernel headers not from /usr/include/linux, use the
configure option --with-headers." "$LINENO" 5
@@ -82,7 +82,7 @@ fi
# 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 "$arch_minimum_kernel" || arch_minimum_kernel=2.6.32
test -n "$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/'`))
@@ -1,7 +1,7 @@
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
# Local configure fragment for sysdeps/unix/sysv/linux.

define([LIBC_LINUX_VERSION],[2.6.32])dnl
define([LIBC_LINUX_VERSION],[3.2.0])dnl
if test -n "$sysheaders"; then
OLD_CPPFLAGS=$CPPFLAGS
CPPFLAGS="$CPPFLAGS $SYSINCLUDES"
@@ -33,7 +33,7 @@ fi
# set arch_minimum_kernel already, let that override our defaults here.
# Note that we presume such a fragment has set libc_cv_gcc_unwind_find_fde
# if appropriate too.
test -n "$arch_minimum_kernel" || arch_minimum_kernel=2.6.32
test -n "$arch_minimum_kernel" || arch_minimum_kernel=3.2.0
if test -n "$minimum_kernel"; then
changequote(,)
user_version=$((`echo "$minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/\1 \* 65536 + \2 \* 256 + \3/'`))
@@ -1,5 +1,7 @@
# This file is generated from configure.ac by Autoconf. DO NOT EDIT!
# Local configure fragment for sysdeps/unix/sysv/linux/i386.

arch_minimum_kernel=2.6.32

libc_cv_gcc_unwind_find_fde=yes
ldd_rewrite_script=sysdeps/unix/sysv/linux/ldd-rewrite.sed
@@ -1,5 +1,7 @@
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
# Local configure fragment for sysdeps/unix/sysv/linux/i386.

arch_minimum_kernel=2.6.32

libc_cv_gcc_unwind_find_fde=yes
ldd_rewrite_script=sysdeps/unix/sysv/linux/ldd-rewrite.sed
@@ -1,6 +1,8 @@
# This file is generated from configure.ac by Autoconf. DO NOT EDIT!
# Local configure fragment for sysdeps/unix/sysv/linux/x86_64/64.

arch_minimum_kernel=2.6.32

test -n "$libc_cv_slibdir" ||
case "$prefix" in
/usr | /usr/)
@@ -1,4 +1,6 @@
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
# Local configure fragment for sysdeps/unix/sysv/linux/x86_64/64.

arch_minimum_kernel=2.6.32

LIBC_SLIBDIR_RTLDDIR([lib64], [lib64])

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