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