From: Andreas Herrmann <andreas.herrmann3@amd.com>
Date: Mon, 8 Jun 2009 13:55:09 +0000 (+0200)
Subject: x86: Detect use of extended APIC ID for AMD CPUs
X-Git-Tag: v2.6.31-rc1~412^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=42937e81a82b6bbc51a309c83da140b3a7ca5945;p=pandora-kernel.git

x86: Detect use of extended APIC ID for AMD CPUs

Booting a 32-bit kernel on Magny-Cours results in the following panic:

  ...
  Using APIC driver default
  ...
  Overriding APIC driver with bigsmp
  ...
  Getting VERSION: 80050010
  Getting VERSION: 80050010
  Getting ID: 10000000
  Getting ID: ef000000
  Getting LVT0: 700
  Getting LVT1: 10000
  Kernel panic - not syncing: Boot APIC ID in local APIC unexpected (16 vs 0)
  Pid: 1, comm: swapper Not tainted 2.6.30-rcX #2
  Call Trace:
   [<c05194da>] ? panic+0x38/0xd3
   [<c0743102>] ? native_smp_prepare_cpus+0x259/0x31f
   [<c073b19d>] ? kernel_init+0x3e/0x141
   [<c073b15f>] ? kernel_init+0x0/0x141
   [<c020325f>] ? kernel_thread_helper+0x7/0x10

The reason is that default_get_apic_id handled extension of local APIC
ID field just in case of XAPIC.

Thus for this AMD CPU, default_get_apic_id() returns 0 and
bigsmp_get_apic_id() returns 16 which leads to the respective kernel
panic.

This patch introduces a Linux specific feature flag to indicate
support for extended APIC id (8 bits instead of 4 bits width) and sets
the flag on AMD CPUs if applicable.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: <stable@kernel.org>
LKML-Reference: <20090608135509.GA12431@alberich.amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

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