lkml.org 
[lkml]   [2009]   [Dec]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
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


\
 
 \ /
  Last update: 2009-12-07 16:51    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site