linux-kernel - Re: [tip:x86/urgent] x86: Detect use of extended APIC ID for AMD CPUs

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Message-ID: <20090608120131.GA8699@alberich.amd.com>
Date:	Mon, 8 Jun 2009 14:01:31 +0200
From:	Andreas Herrmann <andreas.herrmann3@....com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	stable@...nel.org, tglx@...utronix.de,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86: Detect use of extended APIC ID for AMD
	CPUs

On Sun, Jun 07, 2009 at 05:33:27PM +0200, Ingo Molnar wrote:
> 
> * tip-bot for Andreas Herrmann <andreas.herrmann3@....com> wrote:
> 
> > +#ifdef CONFIG_X86_LOCAL_APIC
> > +	/* check CPU config space for extended APIC ID */
> > +	if (c->x86 >= 0xf) {
> > +		unsigned int val;
> > +
> > +		val = read_pci_config(0, 24, 0, 0x68);
> > +		if ((val & ((1 << 17) | (1 << 18))) == ((1 << 17) | (1 << 18)))
> > +			set_cpu_cap(c, X86_FEATURE_EXTD_APICID);
> > +	}
> > +#endif
> 
> It's possible to enable local APIC but not CONFIG_PCI - in that case 
> this sequence will fail to build.

Arrgh, thought that the stuff in early.c is always compiled in. Just
checked arch/x86/pci/Makefile showing
  obj-y                           += common.o early.o
and I didn't check arch/x86/Makefile which contains
  drivers-$(CONFIG_PCI)            += arch/x86/pci/

Sorry.
I'll send an updated patch.


Andreas


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