Messages in this thread | | | Date | Tue, 22 Jul 2008 14:33:06 -0400 | From | Jeff Garzik <> | Subject | Re: Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannot boot |
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H. Peter Anvin wrote: > Jeff Garzik wrote: >>> >>> Thanks for taking a look at this. So well, it would be a >>> misconfiguration bug by the distribution then to try to support a >>> generic 686 kernel wihtout GENERIC then. >> >> Well, it may be intentional -- some distros simply exclude support for >> the lower-volume VIA processors, since that might imply building their >> "generic 686 kernel" sans CMOV and some other instructions, and >> changing the compiler's instruction scheduling to something less >> optimal for the majority. :/ >> > > X86_GENERIC shouldn't disable CMOV?
I said "generic 686 kernel" not a specific Kconfig option (for reasons stated below), which is a bit different.
> We're only referring specifically to the family == 6 VIA processors here.
To be specific, I was merely saying that VIA processors where c->x86_model==6 may lack CMOV.
I have not kept track of what current Kconfig options will set, but in the past it was quite easy to build a "generic 686 kernel" that required CMOV and thus excluded these VIA processors.
Distros in the past often wound up intentionally -not- supporting some of these VIA processors, because they did not want to create a non-CMOV kernel. (This policy obviously excluded older x86 as well)
If these things have been addressed recently (< 12-18 months) then all good.
Jeff
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