From d640113fe80e45ebd4a5b420b220d3f6bf37f682 Mon Sep 17 00:00:00 2001 From: Lin Ming Date: Tue, 13 Dec 2011 09:36:03 +0800 Subject: [PATCH] ACPI: processor: fix acpi_get_cpuid for UP processor For UP processor, it is likely that no _MAT method or MADT table defined. So currently acpi_get_cpuid(...) always return -1 for UP processor. This is wrong. It should return valid value for CPU0. In the other hand, BIOS may define multiple CPU handles even for UP processor, for example Scope (_PR) { Processor (CPU0, 0x00, 0x00000410, 0x06) {} Processor (CPU1, 0x01, 0x00000410, 0x06) {} Processor (CPU2, 0x02, 0x00000410, 0x06) {} Processor (CPU3, 0x03, 0x00000410, 0x06) {} } We should only return valid value for CPU0's acpi handle. And return invalid value for others. http://marc.info/?t=132329819900003&r=1&w=2 Cc: stable@vger.kernel.org Reported-and-tested-by: wallak@free.fr Signed-off-by: Lin Ming Signed-off-by: Len Brown --- drivers/acpi/processor_core.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c index 3a0428e8435c..c850de4c9a14 100644 --- a/drivers/acpi/processor_core.c +++ b/drivers/acpi/processor_core.c @@ -173,8 +173,30 @@ int acpi_get_cpuid(acpi_handle handle, int type, u32 acpi_id) apic_id = map_mat_entry(handle, type, acpi_id); if (apic_id == -1) apic_id = map_madt_entry(type, acpi_id); - if (apic_id == -1) - return apic_id; + if (apic_id == -1) { + /* + * On UP processor, there is no _MAT or MADT table. + * So above apic_id is always set to -1. + * + * BIOS may define multiple CPU handles even for UP processor. + * For example, + * + * Scope (_PR) + * { + * Processor (CPU0, 0x00, 0x00000410, 0x06) {} + * Processor (CPU1, 0x01, 0x00000410, 0x06) {} + * Processor (CPU2, 0x02, 0x00000410, 0x06) {} + * Processor (CPU3, 0x03, 0x00000410, 0x06) {} + * } + * + * Ignores apic_id and always return 0 for CPU0's handle. + * Return -1 for other CPU's handle. + */ + if (acpi_id == 0) + return acpi_id; + else + return apic_id; + } #ifdef CONFIG_SMP for_each_possible_cpu(i) { -- 2.20.1