From: William C. <wc...@nc...> - 2002-08-14 21:38:45
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John Levon wrote: > On Wed, Aug 14, 2002 at 02:37:35PM -0400, William Cohen wrote: > > >>For op_cpu get_cpu_type(void) could be improved. A hard coding of "-1" >>shouldn't be used. If the value is invalid it should be CPU_NO_GOOD. >> > > right > > > >>Also it seems odd that for non X86_VENDOR_AMD everything is CPU_RTC, >>while for X86_VENDOR_AMD everything but hammer returns equivalent to >>CPU_NO_GOOD. Shouldn't it return CPU_RTC for X86_VENDOR_AMD that are >>non-hammer? >> > > is there anything that is x86-64 architectecture but isn't AMD/Hammer ? > :) I am not sure there are non-Hammer x86-64 processors. However, it would be possible and likely that Clawhammer and SledgeHammer have different values for cpuid. I don't know if the things the performance monitoring hardware measure are different between the processors. I know that the Itanium and Itanium 2 performance monitoring hardware have different restrictions and event codes, which require knowing which processor implementation is being used, e.g. 32-bit counters on Itanium vs. 48-bit counters on Itanium 2 and restrictions on which registers can measure which events. Plus, there is the possibility of future different implementations. You can look at Intel documents 245320-003 (Itanium) and 251110-001 (Itanium 2) for the gory details. Dave, could you get some clarification from AMD whether there are differences that the performance monitoring software needs to know about the Hammer implementations? Is AMD going to be smart about this and make sure that newer processors have performance monitoring hardware that is a pure superset of the older hardware? The differences between Itanium and Itanium2 performance monitoring hardware makes this impossible. -Will |