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    SubjectRe: [PATCH 13/13] x86_32: make percpu symbols zerobased on SMP
    Date
    On Tuesday 13 January 2009 21:08:17 Tejun Heo wrote:
    > This patch makes percpu symbols zerobased on x86_32 SMP by using
    > PERCPU_VADDR() with 0 vaddr in vmlinux_32.lds.S. A new PHDR is added
    > as existing ones cannot contain sections near address zero.
    ...
    > Signed-off-by: Tejun Heo <tj@kernel.org>
    > Cc: Mike Travis <travis@sgi.com>
    > ---
    > arch/x86/kernel/cpu/common.c | 8 ++++++++
    > arch/x86/kernel/head_32.S | 37 ++++++++++++++++++++++++++++++++++---
    > arch/x86/kernel/setup_percpu.c | 4 ----
    > arch/x86/kernel/vmlinux_32.lds.S | 16 +++++++++++++++-
    > 4 files changed, 57 insertions(+), 8 deletions(-)

    Hmm, the only reason for this change is to unify with 64-bit, yes? Yet it
    doesn't actually win us anything on that front, as this diffstat shows.

    If gcc's -mcmodel=kernel had used a weak symbol for the offset of the stack
    canary, we would have been happy. Unfortunately generic per-cpu and x86-64
    PDA were developed separately, so noone realize the problem until too late.

    The basic series looks good: it will clash with my per-cpu work (mainly
    because I remove the per_cpu__ prefix) in a purely-textual way though.

    Thanks for this!
    Rusty.


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