x86: add generic clearcpuid=... option

[pandora-kernel.git] / Documentation / kernel-parameters.txt

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 040e30a..50d564d 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -416,6 +416,19 @@ and is between 256 and 4096 characters. It is defined in the file
                        [SPARC64] tick
                        [X86-64] hpet,tsc
 
+       clearcpuid=BITNUM [X86]
+                       Disable CPUID feature X for the kernel. See
+                       include/asm-x86/cpufeature.h for the valid bit numbers.
+                       Note the Linux specific bits are not necessarily
+                       stable over kernel options, but the vendor specific
+                       ones should be.
+                       Also note that user programs calling CPUID directly
+                       or using the feature without checking anything
+                       will still see it. This just prevents it from
+                       being used by the kernel or shown in /proc/cpuinfo.
+                       Also note the kernel might malfunction if you disable
+                       some critical bits.
+
        code_bytes      [IA32/X86_64] How many bytes of object code to print
                        in an oops report.
                        Range: 0 - 8192