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

Ingo Molnar
2009-06-07T15:34:06Z

* tip-bot for Andreas Herrmann <andreas.herrmann3@amd.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