[PATCH 1/2] [PATCH] x86: Look for TSC Deadline Timer
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From: Len Brown on 28 Jul 2010 10:30 From: Len Brown <len.brown(a)intel.com> The new TSC Deadline Timer offers system software a low overhead per-logical-thread deadline timer in TSC units. The timer is implemented via a new architectural 64-bit register, IA32_TSC_DEADLINE_MSR. Reads and writes of this MSR occur in program order, but are non-serializing. The support for this feature is indicated by CPUID.01H:ECX.TSC_Deadline[bit 24] = 1 as documented in the Intel Architectures Software Developer's Manual. This patch discovers support of this feature and displays it as "tdt" in /proc/cpuinfo, and enumeratese the new IA32_TSC_DEADLINE_MSR in kernel headers. Signed-off-by: Len Brown <len.brown(a)intel.com> --- arch/x86/include/asm/cpufeature.h | 1 + arch/x86/include/asm/msr-index.h | 2 ++ 2 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 4681459..b2a47e6 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -120,6 +120,7 @@ #define X86_FEATURE_X2APIC (4*32+21) /* x2APIC */ #define X86_FEATURE_MOVBE (4*32+22) /* MOVBE instruction */ #define X86_FEATURE_POPCNT (4*32+23) /* POPCNT instruction */ +#define X86_FEATURE_TSC_DEADLINE (4*32+24) /* "tdt" TSC Deadline Timer */ #define X86_FEATURE_AES (4*32+25) /* AES instructions */ #define X86_FEATURE_XSAVE (4*32+26) /* XSAVE/XRSTOR/XSETBV/XGETBV */ #define X86_FEATURE_OSXSAVE (4*32+27) /* "" XSAVE enabled in the OS */ diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 8c7ae43..78d0d5b 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -268,6 +268,8 @@ #define MSR_IA32_MISC_ENABLE_TURBO_DISABLE (1ULL << 38) #define MSR_IA32_MISC_ENABLE_IP_PREF_DISABLE (1ULL << 39) +#define MSR_IA32_TSC_DEADLINE 0x000006E0 + /* P4/Xeon+ specific */ #define MSR_IA32_MCG_EAX 0x00000180 #define MSR_IA32_MCG_EBX 0x00000181 -- 1.7.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |