From: Andreas Herrmann Date: Wed, 30 Jan 2008 12:32:41 +0000 (+0100) Subject: x86: fix detection of CONSTANT_TSC bit for AMD CPUs X-Git-Tag: v2.6.25-rc1~1143^2~412 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=9566e91d494ed0668edf88f852de7f251fe8fe9a;p=linux-2.6-omap-h63xx.git x86: fix detection of CONSTANT_TSC bit for AMD CPUs Commits - c52f61fcbdb2aa84f0e4d831ef07f375e6b99b2c (x86: allow TSC clock source on AMD Fam10h and some cleanup) - e30436f05d456efaff77611e4494f607b14c2782 (x86: move X86_FEATURE_CONSTANT_TSC into early cpu feature detection) are supposed to fix the detection of contant TSC for AMD CPUs. Unfortunately on x86_64 it does still not work with current x86/mm. For a Phenom I still get: ... TSC calibrated against PM_TIMER Marking TSC unstable due to TSCs unsynchronized time.c: Detected 2288.366 MHz processor. ... We have to set c->x86_power in early_identify_cpu to properly detect the CONSTANT_TSC bit in early_init_amd. Attached patch fixes this issue. Following the relevant boot messages when the fix is used: ... TSC calibrated against PM_TIMER time.c: Detected 2288.279 MHz processor. ... Initializing CPU#1 ... checking TSC synchronization [CPU#0 -> CPU#1]: passed. ... Initializing CPU#2 ... checking TSC synchronization [CPU#0 -> CPU#2]: passed. ... Booting processor 3/4 APIC 0x3 ... checking TSC synchronization [CPU#0 -> CPU#3]: passed. Brought up 4 CPUs ... Patch is against x86/mm (v2.6.24-rc8-672-ga9f7faa). Please apply. Set c->x86_power in early_identify_cpu. This ensures that X86_FEATURE_CONSTANT_TSC can properly be set in early_init_amd. Signed-off-by: Andreas Herrmann Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c index 3cae326093c..1caf7458dc4 100644 --- a/arch/x86/kernel/setup_64.c +++ b/arch/x86/kernel/setup_64.c @@ -996,6 +996,10 @@ static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c) c->x86_capability[2] = cpuid_edx(0x80860001); } + c->extended_cpuid_level = cpuid_eax(0x80000000); + if (c->extended_cpuid_level >= 0x80000007) + c->x86_power = cpuid_edx(0x80000007); + switch (c->x86_vendor) { case X86_VENDOR_AMD: early_init_amd(c); @@ -1066,11 +1070,6 @@ void __cpuinit identify_cpu(struct cpuinfo_x86 *c) numa_add_cpu(smp_processor_id()); #endif - c->extended_cpuid_level = cpuid_eax(0x80000000); - - if (c->extended_cpuid_level >= 0x80000007) - c->x86_power = cpuid_edx(0x80000007); - switch (c->x86_vendor) { case X86_VENDOR_AMD: early_init_amd(c);