Commit-ID: 0c752a93353d9b17dbe148312d732fbe06d235e1
Gitweb: http://git.kernel.org/tip/0c752a93353d9b17dbe148312d732fbe06d235e1
Author: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
AuthorDate: Fri, 22 May 2009 12:17:45 -0700
Committer: H. Peter Anvin <hpa@xxxxxxxxx>
CommitDate: Fri, 22 May 2009 13:10:54 -0700
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@xxxxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx>
---
Documentation/kernel-parameters.txt | 4 ++++
arch/x86/kernel/cpu/common.c | 7 +++++++
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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