Messages in this thread | | | Date | Mon, 19 Jan 2009 14:24:46 -0800 | From | "H. Peter Anvin" <> | Subject | Re: Fail to early boot with v2.6.27-rc2 to at least v2.6.29-rc2 due to dc1e35c |
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Suresh Siddha wrote: > On Mon, Jan 19, 2009 at 02:07:36PM -0800, H. Peter Anvin wrote: >> Suresh Siddha wrote: >>> Also, I wonder, if we should complain/scream during boot if we find only >>> fewer cpuid levels on modern generation cpu's. >>> >> We should, or if this block is reversible, we should probably just undo >> it (the reason people put this block in places is because of, ahem, >> inferior operating systems having bugs.) >> >> Do you know how this is managed? Via an MSR? > > IA32_MISC_ENABLE MSR bit 22
LOL, the official name of this bit is "IA32_MISC_ENABLES.BOOT_NT4"; kind of says it all. In fact, I remember the problems we had with NT4 and CPUID back from the Transmeta days, and there, too, we ended up with a CPUID hack which Linux unconditionally disables.
I'll write up a patch.
-hpa
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