[Qemu-devel] [PATCH] pc: acpi: keep pvpanic backward compatible

["Radim Krčmář" <rkrcmar@redhat.com>]

In the old times, we always had pvpanic in ACPI and a _STA function told
the guest not to use it.  Now, we only include pvpanic in ACPI if it is
enabled, so the _STA function is useless from qemu's point of view, but
guests still want to query availability.  Make them happy.

This patch extends
  e65bef695441 pc: acpi: fix pvpanic regression

The original _STA method was
  Method (_STA, 0, NotSerialized) {
      Store (PEST, Local0)
      If (LEqual (Local0, Zero)) {
          Return (Zero) }
      Else {
          Return (0x0F) }}

hence we return only 0xf now.
(Why Linux does '& 0xb' on this result is completely beyond me.)

Also, the device used to be PEVT.  (PEVT as in "panic event"?)

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 hw/i386/acpi-build.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 73259e729b9f..4141c110a8e1 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -733,7 +733,7 @@ build_ssdt(GArray *table_data, GArray *linker,
     if (misc->pvpanic_port) {
         scope = aml_scope("\\_SB.PCI0.ISA");
 
-        dev = aml_device("PEVR");
+        dev = aml_device("PEVT");
         aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0001")));
 
         crs = aml_resource_template();
@@ -748,6 +748,10 @@ build_ssdt(GArray *table_data, GArray *linker,
         aml_append(field, aml_named_field("PEPT", 8));
         aml_append(dev, field);
 
+        method = aml_method("_STA", 0);
+        aml_append(method, aml_return(aml_int(0xf)));
+        aml_append(dev, method);
+
         method = aml_method("RDPT", 0);
         aml_append(method, aml_store(aml_name("PEPT"), aml_local(0)));
         aml_append(method, aml_return(aml_local(0)));
-- 
2.4.1