@@ -563,17 +563,21 @@
loops can be debugged more effectively on production
systems.
- clearcpuid=BITNUM [X86]
+ clearcpuid=BITNUM | FLAG [X86]
Disable CPUID feature X for the kernel. See
arch/x86/include/asm/cpufeatures.h for the valid bit
- numbers. Note the Linux specific bits are not necessarily
+ numbers or /proc/cpuinfo for valid CPU flags.
+ Multiple options can be used to disable a few features.
+ This prevents the feature from being used by the
+ kernel or shown in /proc/cpuinfo or shown in CPUID
+ called directly by user programs.
+ A few notes:
+ - 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
+ - User programs using the feature without checking
+ anything will still use it.
+ - The kernel might malfunction if you disable
some critical bits.
cma=nn[MG]@[start[MG][-end[MG]]]
Since kernel option clearcpuid now supports multiple options and CPU capability flags, the document needs to be changed. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> --- .../admin-guide/kernel-parameters.txt | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-)