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    SubjectRe: finding out the boot cpu number from userspace
    > ==> Regarding Re: finding out the boot cpu number from userspace; "Martin J. Bligh" <mbligh@aracnet.com> adds:
    >
    >>> assuming cpu 0 is the boot cpu sounds fragile/incorrect, but for
    >>> irqbalanced I'd like to find out which cpu is the boot cpu, is there a
    >>> good way of doing so ?
    >>>
    >>> The reason for needing this is that some firmware only likes running on
    >>> the boot cpu so I need to bind firmware-related irq's to that cpu
    >>> ideally.
    >
    > mbligh> On any sane arch, cpu 0 *IS* always the boot CPU, as we dynamically
    > mbligh> number CPUs that way ... that doesn't mean that it's apicid 0. I
    > mbligh> believe that PPC64 screwed this up, but AFAIK, everyone else gets
    > mbligh> it correct ... ;-)
    >
    > Hmm, do we need to do any special handling for this in the kexec case?
    > ISTR having some issues with this when using bootimg years back.

    Eric went to some lengths to migrate us back to the original boot CPU
    before kexec'ing. I think this is unnecessary - the new kernel should
    handle booting on any CPU just fine (there was a panic in there at one
    point if the boot CPU didn't match the BIOS's spec'ed one, but I removed
    it).

    M.

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