the following patch was just integrated into master:
commit b60dd4eb5bca71cb70c51b4933b04516fb372258
Author: Stefan Reinauer <[email protected]>
Date: Tue Aug 7 14:44:51 2012 -0700
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 <[email protected]>
Build-Tested: build bot (Jenkins) at Wed Aug 8 23:26:00 2012, giving +1
See http://review.coreboot.org/1422 for details.
-gerrit
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