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Commit 0c752a93 authored May 22, 2009 by Suresh Siddha Committed by H. Peter Anvin May 22, 2009

x86: introduce noxsave boot parameter



Introduce "noxsave" boot parameter which will disable the cpu's xsave/xrstor
capabilities. Useful for debugging and working around xsave related issues.

[ Impact: make it possible to debug problems in the field ]

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

parent bca23dba

Documentation/kernel-parameters.txt

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -1535,6 +1535,10 @@ and is between 256 and 4096 characters. It is defined in the file
	register save and restore. The kernel will only save		register save and restore. The kernel will only save
	legacy floating-point registers on task switch.		legacy floating-point registers on task switch.

			noxsave [BUGS=X86] Disables x86 extended register state save
			and restore using xsave. The kernel will fallback to
			enabling legacy floating-point and sse state.

	nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or		nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
	wfi(ARM) instruction doesn't work correctly and not to		wfi(ARM) instruction doesn't work correctly and not to
	use it. This is also useful when using JTAG debugger.		use it. This is also useful when using JTAG debugger.

arch/x86/kernel/cpu/common.c

+7 −0

Original line number	Original line	Diff line number	Diff line
	@@ -114,6 +114,13 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
	} };		} };
	EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);		EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);

			static int __init x86_xsave_setup(char *s)
			{
			setup_clear_cpu_cap(X86_FEATURE_XSAVE);
			return 1;
			}
			__setup("noxsave", x86_xsave_setup);

	#ifdef CONFIG_X86_32		#ifdef CONFIG_X86_32
	static int cachesize_override __cpuinitdata = -1;		static int cachesize_override __cpuinitdata = -1;
	static int disable_x86_serial_nr __cpuinitdata = 1;		static int disable_x86_serial_nr __cpuinitdata = 1;