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authorSuresh Siddha <suresh.b.siddha@intel.com>2009-05-22 12:17:45 -0700
committerH. Peter Anvin <hpa@zytor.com>2009-05-22 13:10:54 -0700
commit0c752a93353d9b17dbe148312d732fbe06d235e1 (patch)
tree944b37d214dd478abc1c5d2b51573ec87be59c63
parentbca23dba760d6705c013f89113c46570378fb626 (diff)
downloadop-kernel-dev-0c752a93353d9b17dbe148312d732fbe06d235e1.zip
op-kernel-dev-0c752a93353d9b17dbe148312d732fbe06d235e1.tar.gz
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>
-rw-r--r--Documentation/kernel-parameters.txt4
-rw-r--r--arch/x86/kernel/cpu/common.c7
2 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e87bdbf..fd5cac0 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -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
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
wfi(ARM) instruction doesn't work correctly and not to
use it. This is also useful when using JTAG debugger.
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c1caefc..77848d9 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -114,6 +114,13 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
} };
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
static int cachesize_override __cpuinitdata = -1;
static int disable_x86_serial_nr __cpuinitdata = 1;
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