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Re: PATCH: Add x32 dummy sysctl


On Tue, May 22, 2012 at 9:21 AM, Roland McGrath <roland@hack.frob.com> wrote:
>> Step 4. Remove the ABI in X.Y+?
>
> We can never do this without a soname change.
> So, to a first approximation, it will never happen.
>
> That's why it's so important not to let cruft creep in to begin with.
>

This patch adds sysctl.mk and x86-64 sys/sysctl.h, which
issues an error for x32:

#if defined __x86_64__ && defined __ILP32__
# error "sysctl system call is unsupported in x32 kernel"
#endif

Tested on Linux/x32 and Linux/x86-64.  OK to install?

Thanks.


-- 
H.J.
---
	* sysdeps/unix/sysv/linux/Makefile: Include
	$(firstword $(wildcard $(sysdirs:=/sysctl.mk))).
	(sysdep_routines): Replace sysctl with $(sysctl).

	* sysdeps/unix/sysv/linux/sysctl.mk: New file.
	* sysdeps/unix/sysv/linux/x86_64/sys/sysctl.h: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/sysctl.mk: Likewise.

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 120d544..1011509 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -17,7 +17,9 @@ sysdep_routines += internal_accept4 recvmmsg
internal_recvmmsg sendmmsg \
 endif

 ifeq ($(subdir),misc)
-sysdep_routines += sysctl clone llseek umount umount2 readahead \
+include $(firstword $(wildcard $(sysdirs:=/sysctl.mk)))
+
+sysdep_routines += $(sysctl) clone llseek umount umount2 readahead \
 		   setfsuid setfsgid makedev epoll_pwait signalfd \
 		   eventfd eventfd_read eventfd_write prlimit

diff --git a/sysdeps/unix/sysv/linux/sysctl.mk
b/sysdeps/unix/sysv/linux/sysctl.mk
new file mode 100644
index 0000000..e8f2a83
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sysctl.mk
@@ -0,0 +1,3 @@
+ifeq ($(subdir),misc)
+sysctl = sysctl
+endif
diff --git a/sysdeps/unix/sysv/linux/x86_64/sys/sysctl.h
b/sysdeps/unix/sysv/linux/x86_64/sys/sysctl.h
new file mode 100644
index 0000000..c488d99
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/sys/sysctl.h
@@ -0,0 +1,75 @@
+/* Copyright (C) 1996-2012 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
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef	_SYS_SYSCTL_H
+#define	_SYS_SYSCTL_H	1
+
+#if defined __x86_64__ && defined __ILP32__
+# error "sysctl system call is unsupported in x32 kernel"
+#endif
+
+#include <features.h>
+#define __need_size_t
+#include <stddef.h>
+/* Prevent more kernel headers than necessary to be included.  */
+#ifndef _LINUX_KERNEL_H
+# define _LINUX_KERNEL_H	1
+# define __undef_LINUX_KERNEL_H
+#endif
+#ifndef _LINUX_TYPES_H
+# define _LINUX_TYPES_H		1
+# define __undef_LINUX_TYPES_H
+#endif
+#ifndef _LINUX_LIST_H
+# define _LINUX_LIST_H		1
+# define __undef_LINUX_LIST_H
+#endif
+#ifndef __LINUX_COMPILER_H
+# define __LINUX_COMPILER_H	1
+# define __user
+# define __undef__LINUX_COMPILER_H
+#endif
+
+#include <linux/sysctl.h>
+
+#ifdef __undef_LINUX_KERNEL_H
+# undef _LINUX_KERNEL_H
+# undef __undef_LINUX_KERNEL_H
+#endif
+#ifdef __undef_LINUX_TYPES_H
+# undef _LINUX_TYPES_H
+# undef __undef_LINUX_TYPES_H
+#endif
+#ifdef __undef_LINUX_LIST_H
+# undef _LINUX_LIST_H
+# undef __undef_LINUX_LIST_H
+#endif
+#ifdef __undef__LINUX_COMPILER_H
+# undef __LINUX_COMPILER_H
+# undef __user
+# undef __undef__LINUX_COMPILER_H
+#endif
+
+__BEGIN_DECLS
+
+/* Read or write system parameters.  */
+extern int sysctl (int *__name, int __nlen, void *__oldval,
+		   size_t *__oldlenp, void *__newval, size_t __newlen) __THROW;
+
+__END_DECLS
+
+#endif	/* _SYS_SYSCTL_H */
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/sysctl.mk
b/sysdeps/unix/sysv/linux/x86_64/x32/sysctl.mk
new file mode 100644
index 0000000..9f640be
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/sysctl.mk
@@ -0,0 +1,4 @@
+# X32 doesn't support sysctl.
+ifeq ($(subdir),misc)
+sysctl =
+endif


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