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| author | Ingo Molnar <mingo@kernel.org> | 2026-05-29 09:50:59 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2026-05-29 09:51:00 +0200 |
| commit | af9ae836224a746a9bba3a155b7035b60ebd29ce (patch) | |
| tree | b1adbd3d4f0d1058460cd4e7533e87e46507a481 /Documentation | |
| parent | 8fde5d1d47f69db6082dfa34500c27f8485389a5 (diff) | |
| parent | 8aeb879baf12fe64889f019da9a4f8347c604e91 (diff) | |
| download | linux-next-history-af9ae836224a746a9bba3a155b7035b60ebd29ce.tar.gz | |
Merge branch into tip/master: 'x86/urgent'
# New commits in x86/urgent:
8aeb879baf12 ("x86/kvm/vmx: Fix x86_64 CFI build")
a17dc12bfed8 ("x86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines")
cda64169bade ("x86/microcode: Do not access MSR_IA32_PLATFORM_ID when running as a guest")
80501dff814e ("Documentation/arch/x86: Hide clearcpuid=")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 18 | ||||
| -rw-r--r-- | Documentation/arch/x86/cpuinfo.rst | 4 |
2 files changed, 4 insertions, 18 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 4d0f545fb3ec5..97007f4f69d4e 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -789,24 +789,6 @@ Kernel parameters cio_ignore= [S390] See Documentation/arch/s390/common_io.rst for details. - clearcpuid=X[,X...] [X86] - Disable CPUID feature X for the kernel. See - arch/x86/include/asm/cpufeatures.h for the valid bit - numbers X. Note the Linux-specific bits are not necessarily - stable over kernel options, but the vendor-specific - ones should be. - X can also be a string as appearing in the flags: line - in /proc/cpuinfo which does not have the above - instability issue. However, not all features have names - in /proc/cpuinfo. - Note that using this option will taint your kernel. - 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. - clk_ignore_unused [CLK] Prevents the clock framework from automatically gating diff --git a/Documentation/arch/x86/cpuinfo.rst b/Documentation/arch/x86/cpuinfo.rst index 9f2e47c4b1c8e..17fce95367e63 100644 --- a/Documentation/arch/x86/cpuinfo.rst +++ b/Documentation/arch/x86/cpuinfo.rst @@ -187,6 +187,10 @@ to disable features using the feature number as defined in Protection can be disabled using clearcpuid=514. The number 514 is calculated from #define X86_FEATURE_UMIP (16*32 + 2). +DO NOT USE this cmdline option in production - it is meant to be used only as +a quick'n'dirty debugging aid to rule out a feature-enabling code is the +culprit. If you use it, it'll taint the kernel. + In addition, there exists a variety of custom command-line parameters that disable specific features. The list of parameters includes, but is not limited to, nofsgsbase, nosgx, noxsave, etc. 5-level paging can also be disabled using |