From 42937e81a82b6bbc51a309c83da140b3a7ca5945 Mon Sep 17 00:00:00 2001 From: Andreas Herrmann Date: Mon, 8 Jun 2009 15:55:09 +0200 Subject: 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: [] ? panic+0x38/0xd3 [] ? native_smp_prepare_cpus+0x259/0x31f [] ? kernel_init+0x3e/0x141 [] ? kernel_init+0x0/0x141 [] ? 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 Cc: LKML-Reference: <20090608135509.GA12431@alberich.amd.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/amd.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 7e4a459daa6..0802e151c2c 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -6,6 +6,7 @@ #include #include #include +#include #ifdef CONFIG_X86_64 # include @@ -351,6 +352,15 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c) (c->x86_model == 8 && c->x86_mask >= 8)) set_cpu_cap(c, X86_FEATURE_K6_MTRR); #endif +#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PCI) + /* 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 } static void __cpuinit init_amd(struct cpuinfo_x86 *c) -- cgit v1.2.3