Messages in this thread | | | Date | Sun, 5 Jul 2009 23:46:08 +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 12:18:00PM -0700] | Cyrill Gorcunov wrote: | > | > 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. | > | | Well, systems with discrete APICs were few and far between. I'm not | sure if there are any such systems still in meaningful existence (kind | of like Voyager.) That makes it a bit hard to test things, and | certainly means we shouldn't bend over backwards in doing *anything* | that could possibly break other machines. | | -hpa |
Then this patch (eventually) should be dropped. I need to re-check all this.
-- Cyrill
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