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    SubjectRe: [RFC] [PATCH] x86: Use ELF section to list CPU vendor specific code (Linux Tiny)
    Le Mon, 25 Feb 2008 09:03:12 -0800,
    Matt Mackall <mpm@selenic.com> a écrit :

    > > > This is not quite what Peter and I were thinking of, I think.
    > > > It's not at all generic. How about a section that simply contains
    > > > a set of function pointers, a macro to add things to that
    > > > section, and a function that calls all the pointers in that
    > > > section. Eg:
    > > >
    > > > CALLBACK_SECTION(init_cpu_amd, "cpuvendor.init");
    > > > invoke_callback_section("cpuvendor.init");
    > > >
    > > > ..which would give us a generic facility we could use in various
    > > > places.
    > >
    > > I see. Probably doable. How would it work in the LD script file ?
    > > Your mechanism allows to specify any section name, but AFAIK, the
    > > sections must be explicitly listed in the kernel LD script in order
    > > to be included in the final kernel image. Am I missing something ?
    >
    > I can't see any way to avoid it, but we can leave it to future
    > generations to come up with something more clever.

    After a quick look at the LD documentation, it seems that wildcards are
    supported in the input section names of the linker script. So that the
    CALLBACK_SECTION() macro could add the function pointer to a section
    named:

    gcm. ## name

    (gcm standing for "generic callback mechanism") and then, in the linker
    script, do:

    *(gcm.*)

    I'm going to try that.

    Sincerly,

    Thomas
    --
    Thomas Petazzoni, Free Electrons
    Free Embedded Linux Training Materials
    on http://free-electrons.com/training
    (More than 1500 pages!)
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