linux-kernel - Re: APIC: enable workaround on AMD Fam10h CPUs

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Message-ID: <20090204130353.GA15084@aftab>
Date:	Wed, 4 Feb 2009 14:03:53 +0100
From:	Borislav Petkov <borislav.petkov@....com>
To:	Mark Hounschell <markh@...pro.net>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	linux-kernel@...r.kernel.org
Subject: Re: APIC: enable workaround on AMD Fam10h CPUs

On Wed, Feb 04, 2009 at 07:41:12AM -0500, Mark Hounschell wrote:
> Borislav Petkov wrote:
> > From: Borislav Petkov <borislav.petkov@....com>
> > Date: Tue, 3 Feb 2009 16:24:22 +0100
> > Subject: [PATCH] APIC: enable workaround on AMD Fam10h CPUs
> > 
> > Impact: fix to enable APIC for AMD Fam10h on chipsets with a missing/b0rked
> > 	ACPI MP table (MADT)
> > 
> > Booting a 32bit kernel on an AMD Fam10h CPU running on chipsets with
> > missing/b0rked MP table leads to a hang pretty early in the boot process
> > due to the APIC not being initialized. Fix that by falling back to the
> > default APIC base address in 32bit code, as it is done in the 64bit
> > codepath.
> > 
> > Signed-off-by: Borislav Petkov <borislav.petkov@....com>
> > ---
> >  arch/x86/kernel/apic.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/apic.c b/arch/x86/kernel/apic.c
> > index 4b6df24..115449f 100644
> > --- a/arch/x86/kernel/apic.c
> > +++ b/arch/x86/kernel/apic.c
> > @@ -1436,7 +1436,7 @@ static int __init detect_init_APIC(void)
> >  	switch (boot_cpu_data.x86_vendor) {
> >  	case X86_VENDOR_AMD:
> >  		if ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model > 1) ||
> > -		    (boot_cpu_data.x86 == 15))
> > +		    (boot_cpu_data.x86 >= 15))
> >  			break;
> >  		goto no_apic;
> >  	case X86_VENDOR_INTEL:
> 
> Hi Borislav,
> 
> Could this have anything to do with my Phenom-II problem that you've been so kind
> to help me with?
> 
> Thanks
> Mark
>

Well, we thought so originally but since a 64bit kernel fails booting
on your machine too, it can't be it because this is a 32bit codepath
issue.

Another question: does your machine boot a tickless kernel (CONFIG_NO_HZ enabled)?

-- 
Regards/Gruss,
Boris.

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