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    SubjectRe: [patch 05/14] percpu: Use a Kconfig variable to configure arch specific percpu setup
    On Wed, 28 Nov 2007, Rusty Russell wrote:

    > On Wednesday 28 November 2007 05:14:47 Christoph Lameter wrote:
    > > On Tue, 27 Nov 2007, Rusty Russell wrote:
    > > > Have you considered moving x86-64's setup_per_cpu_areas into generic
    > > > code? It's a bit messier because some archs might not have set up NUMA
    > > > stuff yet, but it's logically generic...
    > >
    > > Yes that will happen later. This is just the early cleanup work. I
    > > plan to generally bring the two x86 arches in line. The pda will be
    > > folded into the per cpu area and after that its easy to do.
    > Unfortunately, we tried to get rid of the x86-64 pda (like i386) but you lose
    > the ability to use the stack protection config option. That's because it
    > assumes that gs:0x68 (or something) is the stack canary; we need a YA gcc
    > change to make this gs:__builtin_stack_canary_off (where gcc can emit
    > __builtin_stack_canary_off as a weak absolute symbol, so we can override it
    > for the kernel.

    This works if you rebase the per cpu area at zero. gs:0x68 is still the
    stack canary.

    The i386 method does not work because the segment register does not
    directly point to the pda.

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      Last update: 2007-11-28 19:53    [W:0.022 / U:5.844 seconds]
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