linux-kernel - Re: [tip:x86/urgent] x86: Fix bogus warning in apic_noop.apic

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Message-ID: <20091207150425.GA5489@lenovo>
Date:	Mon, 7 Dec 2009 18:04:25 +0300
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	tglx@...utronix.de, mingo@...e.hu
Cc:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86: Fix bogus warning in
	apic_noop.apic_write()

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@...utronix.de>
> AuthorDate: Mon, 7 Dec 2009 12:59:46 +0100
> Committer:  Ingo Molnar <mingo@...e.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@...utronix.de>
> Cc: Cyrill Gorcunov <gorcunov@...nvz.org>
> Cc: <stable@...nel.org> # in <= .32 this typo resides in native_apic_write_dummy()
> LKML-Reference: <alpine.LFD.2.00.0912071255420.3089@...alhost.localdomain>
> Signed-off-by: Ingo Molnar <mingo@...e.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.

	-- Cyrill
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