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    SubjectRe: missing .data.shared_align placement in vmlinux
    On Fri, May 21, 2010 at 04:58:53PM -0400, Mike Frysinger wrote:
    > am i missing something or does the .data.shared_align section lack
    > definition in vmlinux.lds.h and all arch vmlinux.lds.S files ?
    >
    > with the recent change "net: remove time limit in process_backlog()",
    > the softnet_data variable changed from "DEFINE_PER_CPU()" to
    > "DEFINE_PER_CPU_ALIGNED()" which moved it from the .data section to
    > the .data.shared_align section. i'm not saying this patch is wrong,
    > just that is what caused me to notice this larger problem. no one
    > else in the kernel is using this aligned macro variant, so i imagine
    > that's why no one has noticed yet.
    >
    > since .data.shared_align isnt declared in any vmlinux files that i can
    > see, the linker just places it last. this "just works" for most
    > people, but when building a ROM kernel on Blackfin systems, it causes
    > section overlap errors:
    > bfin-uclinux-ld.real: section .init.data [00000000202e06b8 ->
    > 00000000202e48b7] overlaps section .data.shared_aligned
    > [00000000202e06b8 -> 00000000202e0723]
    > i imagine other arches which support the ROM config option and thus do
    > funky placement would see similar issues ...
    >
    > on x86, it is stuck in a dedicated section:
    > [ 8] .data PROGBITS ffffffff810ec000 2ec000
    > 0303a8 00 WA 0 0 4096
    > [ 9] .data.shared_alig PROGBITS ffffffff8111c3c0 31c3c0
    > 0000c8 00 WA 0 0 64
    >
    > the ifdef forest in asm-generic/percpu.h is beyond a quick glance &
    > fix, so i leave it up to someone else ;)

    as there any resolution on this?
    I briefly looked at it some time ago.
    And it looks like a plain oversight.

    But I was also a bit lost in the forest of ifdef land...

    Sam


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