Subj : Re: AMD has cmpxchg16b now - sort of To : comp.programming.threads From : Joe Seigh Date : Mon Mar 07 2005 05:29 pm On Mon, 07 Mar 2005 21:43:16 GMT, David Hopwood wrote: > Joe Seigh wrote: >> The latest architecture manual (Feb 2005) for AMD 64 bit processors shows >> cmpxchg16b as an instruction now. Except it's a processor feature. And >> it turns out cmpxchg16b is a processor feature for Intel 64 bit extensions >> as well. Powerpc is looking more and more attractive. > > Of course it's a processor feature. You didn't expect them to declare all > existing Athlon64s noncompliant, did you? Although they introduced the new features midstream, making it an option probably wasn't the best way to go. That conbined with no external documentation on what processor models have what features makes it impossible to determine if the processor has the feature before buying it. They probably should have gone with a architectural version numbering scheme that let you know at what point features become committed to the architecture. > > (And of course it's a processor feature for EM64T if it is for AMD64.) > AFAIK cmpxchg16b was in EM64T before it was in AMD64. -- Joe Seigh .