Messages in this thread | | | Date | Sun, 5 Jul 2009 23:02:11 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [RFC -tip] x86,apic -- reduce disable_apic usage |
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[H. Peter Anvin - Sun, Jul 05, 2009 at 10:30:11AM -0700] | Maciej W. Rozycki wrote: | > | > How do you set cpu_has_apic for systems with discrete local APICs? The | > CPUID flag is not set in this case. | > | | Well, should it be? We do set flags when they're appropriate to us, and | if the semantics are such as that is inappropriate we can set a custom bit. | | -hpa |
Peter, Maciej but how kernel behaved on older cpu long time ago?
I mean -- should user pass "lapic" cmdline option too be able to use apic functionality? (i'm asking since I just don't know how it had been working before). Current code (if only I'm not _missing_ something) relies on cpu_has_apic bit. And even if MP table has been parsed and APIC base found, cpu_has_apic could be not set so detect_init_APIC will fail if no "lapic" option passed (in case of old cpu without this cpuid bit produced) as we eventually stay with pic mode.
-- Cyrill
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