From 0db6820b10c3452764ab62173c3b75cefbf6c215 Mon Sep 17 00:00:00 2001 From: Stefan Reinauer Date: Tue, 7 Aug 2012 14:44:51 -0700 Subject: Synchronize rdtsc instructions The CPU can arbitrarily reorder calls to rdtsc, significantly reducing the precision of timing using the CPUs time stamp counter. Unfortunately the method of synchronizing rdtsc is different on AMD and Intel CPUs. There is a generic method, using the cpuid instruction, but that uses up a lot of registers, and is very slow. Hence, use the correct lfence/mfence instructions (for CPUs that we know support it) Change-Id: I17ecb48d283f38f23148c13159aceda704c64ea5 Signed-off-by: Stefan Reinauer Reviewed-on: http://review.coreboot.org/1422 Reviewed-by: Alexandru Gagniuc Tested-by: build bot (Jenkins) --- src/cpu/amd/model_10xxx/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'src/cpu/amd/model_10xxx/Kconfig') diff --git a/src/cpu/amd/model_10xxx/Kconfig b/src/cpu/amd/model_10xxx/Kconfig index 221d0449ac..0890771e34 100644 --- a/src/cpu/amd/model_10xxx/Kconfig +++ b/src/cpu/amd/model_10xxx/Kconfig @@ -3,6 +3,7 @@ config CPU_AMD_MODEL_10XXX select SSE select SSE2 select MMCONF_SUPPORT_DEFAULT + select TSC_SYNC_LFENCE if CPU_AMD_MODEL_10XXX config CPU_ADDR_BITS -- cgit v1.2.3