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Commit d944d549 authored Feb 20, 2010 by Russell King

ARM: allow alignment fault mode to be configured at kernel boot



Some glibc versions intentionally create lots of alignment faults in
their gconv code, which if not fixed up, results in segfaults during
boot.  This can prevent systems booting properly.

There is no clear hard-configurable default for this; the desired
default depends on the nature of the userspace which is going to be
booted.

So, provide a way for the alignment fault handler to be configured via
the kernel command line.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent 0fa11802

Documentation/kernel-parameters.txt

+5 −0

Original line number	Diff line number	Diff line
		@@ -315,6 +315,11 @@ and is between 256 and 4096 characters. It is defined in the file
		aic79xx= [HW,SCSI]
		See Documentation/scsi/aic79xx.txt.

		alignment= [KNL,ARM]
		Allow the default userspace alignment fault handler
		behaviour to be specified. Bit 0 enables warnings,
		bit 1 enables fixups, and bit 2 sends a segfault.

		amd_iommu= [HW,X86-84]
		Pass parameters to the AMD IOMMU driver in the system.
		Possible values are:

arch/arm/mm/alignment.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -11,6 +11,7 @@
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*/
		#include <linux/moduleparam.h>
		#include <linux/compiler.h>
		#include <linux/kernel.h>
		#include <linux/errno.h>
		@@ -77,6 +78,8 @@ static unsigned long ai_dword;
		static unsigned long ai_multi;
		static int ai_usermode;

		core_param(alignment, ai_usermode, int, 0600);

		#define UM_WARN (1 << 0)
		#define UM_FIXUP (1 << 1)
		#define UM_SIGNAL (1 << 2)