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    SubjectRe: i386 PDA patches use of %gs
    Ingo Molnar wrote:
    > for example, your test_fs() code does:
    > for(i = 0; i < COUNT; i++) {
    > asm volatile("push %%fs; mov %1, %%fs; addl $1, %%fs:%0; popl %%fs"
    > : "+m" (*offset): "r" (seg) : "memory");
    > sync();
    > }
    > that loads (and uses) a single selector value for %fs, and doesnt do any
    > mixed use as far as i can see.

    I'm not sure what you're getting at. Each loop iteration is analogous
    to a user->kernel->user transition with respect to the
    save/reload/use/restore pattern on the segment register. In this case,
    %fs starts as a null selector, gets reloaded with a non NULL selector,
    and then is restored to null. Do you mean some other mixing?

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      Last update: 2006-11-15 19:45    [W:0.019 / U:2.688 seconds]
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