diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 13 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 11 | ||||
| -rw-r--r-- | arch/x86/kernel/setup_64.c | 11 |
3 files changed, 35 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 040e30a33b7c..50d564dabb13 100644 --- 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 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 56b7ea8e6c79..56cc341cc586 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -572,6 +572,17 @@ void __cpuinit print_cpu_info(struct cpuinfo_x86 *c) printk("\n"); } +static __init int setup_disablecpuid(char *arg) +{ + int bit; + if (get_option(&arg, &bit) && bit < NCAPINTS*32) + setup_clear_cpu_cap(bit); + else + return 0; + return 1; +} +__setup("clearcpuid=", setup_disablecpuid); + cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE; /* This is hacky. :) diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c index cb9b8a90c094..79635b7bd57a 100644 --- a/arch/x86/kernel/setup_64.c +++ b/arch/x86/kernel/setup_64.c @@ -1050,6 +1050,17 @@ void __cpuinit print_cpu_info(struct cpuinfo_x86 *c) printk(KERN_CONT "\n"); } +static __init int setup_disablecpuid(char *arg) +{ + int bit; + if (get_option(&arg, &bit) && bit < NCAPINTS*32) + setup_clear_cpu_cap(bit); + else + return 0; + return 1; +} +__setup("clearcpuid=", setup_disablecpuid); + /* * Get CPU information for use by the procfs. */ |