Messages in this thread | | | Date | Wed, 22 Oct 2008 16:52:40 +0100 (BST) | From | "Maciej W. Rozycki" <> | Subject | Re: [PATCH -tip] x86: do_boot_cpu - check if we have ESR register |
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On Wed, 22 Oct 2008, Ingo Molnar wrote:
> ah, Compaq - how many CPUs does that box support? If it's 8 or more then > perhaps they turned off the real local APIC, fudged some chipset glue to > emulate APIC functionality and thus were able to use 8 or more of these > chips? The built-in lapic would only go up to 4 CPUs. (or maybe even > just up to dual, depending on the model)
Hmm, interesting. The integrated APIC should support up to 14 CPUs (assuming one ID is needed for the I/O APIC). One cannot preclude silicon errata affecting the less common hardware configurations though. It would be interesting to see a full bootstrap log with all the APIC debug information enabled. That would probably clarify matters a bit.
Note that Compaq would have to come with their own solution about the discrete APIC as the 82489DX went out of production many years ago -- ten at the very least. OTOH, they could have stockpiled them back then. ;) This is one of the few manufacturers I would actually suspect doing so as they always seemed keen on going SMP. Good to know we can support these boxes at all these days.
> This reminds us that all the is-integrated-lapic checks still matter > today.
Quite surprising indeed.
Maciej
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