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>
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index bb83b1c..78dee4f 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -94,6 +94,7 @@
#define X86_FEATURE_TSC_RELIABLE (3*32+23) /* TSC is known to be reliable */
#define X86_FEATURE_NONSTOP_TSC (3*32+24) /* TSC does not stop in C states */
#define X86_FEATURE_CLFLUSH_MONITOR (3*32+25) /* "" clflush reqd with monitor */
+#define X86_FEATURE_EXTD_APICID (3*32+26) /* has extended APICID (8 bits) */
/* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
#define X86_FEATURE_XMM3 (4*32+ 0) /* "pni" SSE-3 */