Messages in this thread | | | Date | Sat, 09 Aug 2003 10:05:18 -0400 | From | Jeff Garzik <> | Subject | Re: [patch 2.4 1/2] backport 2.6 x86 cpu capabilities |
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Mikael Pettersson wrote: > On Fri, 08 Aug 2003 09:15:03 -0400, Jeff Garzik wrote: > >>>If you change NCAPINTS you also have to change the hardcoded >>>struct offset X86_VENDOR_ID in arch/i386/kernel/head.S. Otherwise >>>nasty stuff happen at boot since boot_cpu_data gets broken. >> >> >>hmmm, reality doesn't seem to bear that out... I made the same change >>to 2.6, without touching head.S, and life continues without "nasty >>stuff" AFAICS. >> >>Do both 2.4 and 2.6 need this change? And, why didn't 2.6 break? > > > 2.4.21-rc1 with NCAPINTS==6 hangs at boot in the local > APIC timer calibration step; before that it detected a > 0MHz bus clock and the local APIC NMI watchdog was stuck. > Correcting head.S:X86_VENDOR_ID fixes these problems. > > Without correcting head.S:X86_VENDOR_ID, head.S will store > the vendor id partly in the capabilities array. This breaks > both the capabilities and the vendor id. I can't say why 2.6 > works, but obviously the CPU setup code has changed since 2.4. > > BTW, the patch below should be applied to 2.6.
Thanks for the patch, and for explaining.
Jeff
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