From cb2ded37fd2e1039f96c8c892da024a8f033add5 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Tue, 4 Jan 2011 16:38:52 -0800 Subject: x86: Fix APIC ID sizing bug on larger systems, clean up MAX_APICS confusion Found one x2apic pre-enabled system, x2apic_mode suddenly get corrupted after register some cpus, when compiled CONFIG_NR_CPUS=255 instead of 512. It turns out that generic_processor_info() ==> phyid_set(apicid, phys_cpu_present_map) causes the problem. phys_cpu_present_map is sized by MAX_APICS bits, and pre-enabled system some cpus have an apic id > 255. The variable after phys_cpu_present_map may get corrupted silently: ffffffff828e8420 B phys_cpu_present_map ffffffff828e8440 B apic_verbosity ffffffff828e8444 B local_apic_timer_c2_ok ffffffff828e8448 B disable_apic ffffffff828e844c B x2apic_mode ffffffff828e8450 B x2apic_disabled ffffffff828e8454 B num_processors ... Actually phys_cpu_present_map is referenced via apic id, instead index. We should use MAX_LOCAL_APIC instead MAX_APICS. For 64-bit it will be 32768 in all cases. BSS will increase by 4k bytes on 64-bit: text data bss dec filename 21696943 4193748 12787712 38678403 vmlinux.before 21696943 4193748 12791808 38682499 vmlinux.after No change on 32bit. Finally we can remove MAX_APCIS that was rather confusing. Signed-off-by: Yinghai Lu Cc: H. Peter Anvin Cc: "Eric W. Biederman" LKML-Reference: <4D23BD9C.3070102@kernel.org> Signed-off-by: Ingo Molnar --- arch/x86/kernel/acpi/boot.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/x86/kernel/acpi') diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index 7235e5fbdb6..17c8090fabd 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -915,13 +915,13 @@ static int __init acpi_parse_madt_lapic_entries(void) acpi_register_lapic_address(acpi_lapic_addr); count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_SAPIC, - acpi_parse_sapic, MAX_APICS); + acpi_parse_sapic, MAX_LOCAL_APIC); if (!count) { x2count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_X2APIC, - acpi_parse_x2apic, MAX_APICS); + acpi_parse_x2apic, MAX_LOCAL_APIC); count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC, - acpi_parse_lapic, MAX_APICS); + acpi_parse_lapic, MAX_LOCAL_APIC); } if (!count && !x2count) { printk(KERN_ERR PREFIX "No LAPIC entries present\n"); -- cgit v1.2.3-70-g09d2