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Diffstat (limited to 'drivers/acpi/processor_core.c')
-rw-r--r--drivers/acpi/processor_core.c26
1 files 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) {