From: Andreas Herrmann Date: Thu, 18 Sep 2008 19:12:10 +0000 (+0200) Subject: x86: c1e_idle: don't mark TSC unstable if CPU has invariant TSC X-Git-Tag: upstream/snapshot3+hdmi~22619^2~2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=09bfeea13cea843fb03eaa96b5d891fa0abdcc90;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git x86: c1e_idle: don't mark TSC unstable if CPU has invariant TSC Impact: Functional TSC is marked unstable on AMD family 0x10 and 0x11 CPUs. This would be wrong because for those CPUs "invariant TSC" means: "The TSC counts at the same rate in all P-states, all C states, S0, or S1" (See "Processor BIOS and Kernel Developer's Guides" for those CPUs.) [ tglx: Changed C1E to AMD C1E in the printks to avoid confusion with Intel C1E ] Signed-off-by: Andreas Herrmann Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index d8c2a299..876e918 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -270,8 +270,9 @@ static void c1e_idle(void) rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi); if (lo & K8_INTP_C1E_ACTIVE_MASK) { c1e_detected = 1; - mark_tsc_unstable("TSC halt in C1E"); - printk(KERN_INFO "System has C1E enabled\n"); + if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) + mark_tsc_unstable("TSC halt in AMD C1E"); + printk(KERN_INFO "System has AMD C1E enabled\n"); set_cpu_cap(&boot_cpu_data, X86_FEATURE_AMDC1E); } }