diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/acpi/processor_core.c | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c index 3a0428e8435..c850de4c9a1 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) { |