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    SubjectRe: [patch 8/9] F00F bug fixup for i386 - use conditional calls
    * Andrew Morton (akpm@linux-foundation.org) wrote:
    > On Thu, 31 May 2007 17:07:55 -0400
    > Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:
    >
    > > * Andrew Morton (akpm@linux-foundation.org) wrote:
    > >
    > > > > Use the faster conditional calls for F00F bug handling in do_page_fault.
    > > > >
    > > >
    > > > I guess this means that CONDCALL will be enabled on pretty much all i386,
    > > > in which case making the whole feature Kconfigurable is starting to look
    > > > marginal.
    > > >
    > > > Perhaps a better approach would have to made this change dependent upon
    > > > CONDCALL, rather than forcing it on.
    > > >
    > >
    > > Do you mean making X86_F00F_BUG depend on COND_CALL instead of selecting
    > > it ?
    >
    > yup
    >
    > > > > + if (cond_call(fix_f00f, do_f00f_workaround(regs, address)))
    > > > > + return;
    > > >
    > > > We do a cond_call() to an inlined function? That's a bit weird, isn't it?
    > > >
    > >
    > > Yes, but it works :) I will add this information to the documentation.
    >
    > But why does it work? Did the compiler generate an out-of-line copy
    > of the function? If so, we'll end up with multiple copies of the function if
    > there are other callers. If not, the `inline' was pointless.

    Yes, it's doing an out-of-line copy. Just like the compiler would have
    done if we place a call to an inline function within a if() { } block.

    --
    Mathieu Desnoyers
    Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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