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    SubjectRe: [tip:x86/urgent] x86: Fix bogus warning in apic_noop.apic_write()
    On Mon, 7 Dec 2009, Cyrill Gorcunov wrote:
    > On Mon, Dec 07, 2009 at 12:18:37PM +0000, tip-bot for Thomas Gleixner wrote:
    > > Commit-ID: a946d8f11f0da9cfc714248036fcfd3a794d1e27
    > > Gitweb: http://git.kernel.org/tip/a946d8f11f0da9cfc714248036fcfd3a794d1e27
    > > Author: Thomas Gleixner <tglx@linutronix.de>
    > > AuthorDate: Mon, 7 Dec 2009 12:59:46 +0100
    > > Committer: Ingo Molnar <mingo@elte.hu>
    > > CommitDate: Mon, 7 Dec 2009 13:16:37 +0100
    > >
    > > x86: Fix bogus warning in apic_noop.apic_write()
    > >
    > > apic_noop is used to provide dummy apic functions. It's installed
    > > when the CPU has no APIC or when the APIC is disabled on the kernel
    > > command line.
    > >
    > > The apic_noop implementation of apic_write() warns when the CPU has
    > > an APIC or when the APIC is not disabled.
    > >
    > > That's bogus. The warning should only happen when the CPU has an
    > > APIC _AND_ the APIC is not disabled. apic_noop.apic_read() has the
    > > correct check.
    > >
    > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    > > Cc: Cyrill Gorcunov <gorcunov@openvz.org>
    > > Cc: <stable@kernel.org> # in <= .32 this typo resides in native_apic_write_dummy()
    > > LKML-Reference: <alpine.LFD.2.00.0912071255420.3089@localhost.localdomain>
    > > Signed-off-by: Ingo Molnar <mingo@elte.hu>
    > > ---
    > > arch/x86/kernel/apic/apic_noop.c | 2 +-
    > > 1 files changed, 1 insertions(+), 1 deletions(-)
    > ...
    >
    > Hi Thomas, Ingo,
    >
    > please do not change it. There are still machines without
    > cpu_has_apic bit support so with this patch any attempt
    > to write to 82489DX will success. So the former code has
    > been using "OR" by a purpose, there is no error.

    Err, your warning has the following false positive:

    cpu_has_apic == true and disable_apic == true

    Which is crap, as it warns just because someone disabled the APIC on
    the command line and the kernel did the right thing of installing
    apic_noop.

    And I have a hard time to see how this is related to 82489DX.

    Thanks,

    tglx


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