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[9/9] pc: acpi: clarify why possible LAPIC entries must be present in MADT

Message ID 1454586455-10202-9-git-send-email-imammedo@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Igor Mammedov Feb. 4, 2016, 11:47 a.m. UTC
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 hw/i386/acpi-build.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Eduardo Habkost Feb. 5, 2016, 3:39 p.m. UTC | #1
On Thu, Feb 04, 2016 at 12:47:35PM +0100, Igor Mammedov wrote:
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
diff mbox

Patch

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index d6cd06a..2cc3fff 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -361,6 +361,12 @@  build_madt(GArray *table_data, GArray *linker,
         if (id.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);
         }
     }