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    SubjectRe: [PATCH 1/2 #tj-percpu] x86: fix build breakage on voyage
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    On Tue, 2009-01-27 at 20:47 +0900, Tejun Heo wrote:
    > Hello, Ingo.
    >
    > Ingo Molnar wrote:
    > >> +#ifdef CONFIG_X86_LOCAL_APIC
    > >> early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
    > >> early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
    > >> +#endif
    > >
    > > That patch is not acceptable - it is ugly and it adds another set of
    > > #ifdefs to an already complex piece of code.
    >
    > Well, although the patch itself does add #ifdef, if you look over the
    > whole series, voyager is now a much more conforming citizen in the x86
    > world. There are several solutions to this particular one.
    >
    > 1. Just let apic stuff defined and not use it in voyager if the ifdef
    > is disturbing. IIUC, apic isn't used in voyager at all, right?
    >
    > 2. Clean up early percpu stuff so that it each early percpu variable
    > doesn't need to be explicitly copied and cleared, which is the
    > actual problem here.

    Right ... there's a variant of this where the copying and clearing is
    done within the actual file that defines the variable (i.e. a hook
    approach).

    > 3. But, then again, the current interim and ugly way of doing it isn't
    > too bad considering the small number of early per cpu users.
    >
    > To me the current form doesn't look too bad but if it's too ugly,
    > maybe doing #2 is not such a bad idea such that early percpu can be
    > transferred to percpu in more systematic way. It still feels a bit
    > like overdoing it tho.
    >
    > What do you think?

    What's the actual goal of setup_percpu.c? To have a single location for
    all the per_cpu initialisation? If so then it's hard to get away from
    all the ifdefs. If there are alternative ways of arranging the file
    then I think splitting some of the conditional pieces into other files
    would work.

    James




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