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    SubjectRe: [PATCH] x86: APIC: Remove apic_write_around(); use alternatives

    * Maciej W. Rozycki <macro@linux-mips.org> wrote:

    > Use alternatives to select the workaround for the 11AP Pentium
    > erratum for the affected steppings on the fly rather than build time.
    > Remove the X86_GOOD_APIC configuration option and replace all the
    > calls to apic_write_around() with plain apic_write(), protecting
    > accesses to the ESR as appropriate due to the 3AP Pentium erratum.
    > Remove apic_read_around() and all its invocations altogether as not
    > needed. Remove apic_write_atomic() and all its implementing backends.
    > The use of ASM_OUTPUT2() is not strictly needed for input constraints,
    > but I have used it for readability's sake.

    wow, impressive patch!

    > I had the feeling no one else was brave enough to do it, so I went
    > ahead and here it is. Verified by checking the generated assembly and
    > tested with both a 32-bit and a 64-bit configuration, also with the
    > 11AP "feature" forced on and verified with gdb on /proc/kcore to work
    > as expected (as an 11AP machines are quite hard to get hands on these
    > days). Some script complained about the use of "volatile", but
    > apic_write() needs it for the same reason and is effectively a
    > replacement for writel(), so I have disregarded it.

    kudos for pulling this off :-)

    applied to tip/x86/apic. This will interact with tip/x86/x2apic but that
    topic is being worked on anyway. The interaction should be trivial.

    Ingo


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