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

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Date:	Sun, 7 Jun 2009 17:33:27 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	andreas.herrmann3@....com, stable@...nel.org, tglx@...utronix.de
Cc:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86: Detect use of extended APIC ID for AMD
	CPUs


* 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.

	Ingo
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