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x86: introduce noxsave boot parameter

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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>
This commit is contained in:
Suresh Siddha 2009-05-22 12:17:45 -07:00 committed by H. Peter Anvin
parent bca23dba76
commit 0c752a9335
2 changed files with 11 additions and 0 deletions
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4
Documentation/kernel-parameters.txt
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@ -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.

7
arch/x86/kernel/cpu/common.c
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@ -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;