pc: acpi: clarify why possible LAPIC entries must be present in MADT

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Igor Mammedov 2016-02-26 14:59:27 +01:00 committed by Michael S. Tsirkin
parent adcb89d55d
commit ed2ef10c0c

View File

@ -360,6 +360,12 @@ build_madt(GArray *table_data, GArray *linker, PCMachineState *pcms)
if (apic_ids->cpus[i].cpu != NULL) {
apic->flags = cpu_to_le32(1);
} else {
/* ACPI spec says that LAPIC entry for non present
* CPU may be omitted from MADT or it must be marked
* as disabled. However omitting non present CPU from
* MADT breaks hotplug on linux. So possible CPUs
* should be put in MADT but kept disabled.
*/
apic->flags = cpu_to_le32(0);
}
}