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Date:   Tue, 12 Mar 2019 16:00:36 -0700
From:   Fenghua Yu <>
To:     "Thomas Gleixner" <>,
        "Ingo Molnar" <>, "H Peter Anvin" <>,
        "Dave Hansen" <>,
        "Paolo Bonzini" <>,
        "Ashok Raj" <>,
        "Peter Zijlstra" <>,
        "Xiaoyao Li " <>,
        "Michael Chan" <>,
        "Ravi V Shankar" <>
Cc:     "linux-kernel" <>,
        "x86" <>,,,,
        Fenghua Yu <>
Subject: [PATCH v5 18/18] Change document for kernel option clearcpuid

Since kernel option clearcpuid now supports multiple options and CPU
capability flags, the document needs to be changed.

Signed-off-by: Fenghua Yu <>
 Documentation/admin-guide/kernel-parameters.txt | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2b8ee90bb644..7e65ae67d573 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -563,10 +563,12 @@
 			loops can be debugged more effectively on production
-	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.
+			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

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