On Thu, Oct 31, 2013 at 03:49:04PM +0100, Paolo Bonzini wrote: > Il 31/10/2013 15:34, Gleb Natapov ha scritto: > > I haven't checked AMD doc, but if it is documented that lahf/sahf #UDs at 64 > > bit we should emulate it correctly. > > It says "The LAHF instruction can only be executed in 64-bit mode if > supported by the processor implementation. Check the status of ECX bit 0 > returned by CPUID function 8000_0001h to verify that the processor > supports LAHF in 64-bit mode". Same as Intel---in fact 80000001h is an > "AMD leaf" so to speak. > > I found "AMD introduced support for the instructions with their Athlon > 64, Opteron and Turion 64 revision D processors in March 2005 and Intel > introduced support for the instructions with the Pentium 4 G1 stepping > in December 2005". I think we can for all practical purposes ignore the > lahf_lm CPUID flag. > Yep, Reviewed-by: Gleb Natapov <gleb@xxxxxxxxxx> -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html