Re: [Qemu-devel] [PATCH] Add option to disable FDC from ISA bus and ACPI on i386

["Gabriel L. Somlo" <gsomlo@gmail.com>]

On Wed, Jan 08, 2014 at 11:13:54PM +0100, Paolo Bonzini wrote:
> Have you played with the HPET device?  It would be nice to have Mac OS X
> support in QEMU 2.0.

I remember telling you that the HPET needed an extra ACPI patch
(enclosed again below for reference) to work with OS X, and that
this patch conflicts with XP.

In the mean time, after some tinkering, it turns out that Q35 works
fine without the patch. On PIIX, xnu crashes during boot with a "no
HPET found" panic unless the patch is applied.

At this point, I'm tempted to just write off PIIX + OS X and declare
Q35 as the only "supported" machine type, to keep things simple and
avoid complicating the HPET ACPI code with if/then/else logic that
depends on the return value of SMC._STA(), etc.

Let me know what you all think.

Thanks,
--Gabriel

P.S. Another OS X issue is getting e1000 to "link up" (but in an earlier
conversation it was decided that guest-specific hacks belong in the BIOS
rather than in QEMU, so I still have a "todo" item to figure out where
to put that patch, and how :)

###############################################################################
# Modify DSDT entry for HPET: conditionally insert "IRQNoFlags() {2, 8}" into
# _CRS method only if an AppleSMC chip is present and enabled (otherwise, this
# will cause WinXP to BSOD).
# NOTE: not needed with q35, but necessary on piix !!!
###############################################################################
diff --git a/hw/i386/acpi-dsdt-hpet.dsl b/hw/i386/acpi-dsdt-hpet.dsl
index dfde174..2a0158a 100644
--- a/hw/i386/acpi-dsdt-hpet.dsl
+++ b/hw/i386/acpi-dsdt-hpet.dsl
@@ -38,14 +38,23 @@ Scope(\_SB) {
             }
             Return (0x0F)
         }
-        Name(_CRS, ResourceTemplate() {
-#if 0       /* This makes WinXP BSOD for not yet figured reasons. */
-            IRQNoFlags() {2, 8}
-#endif
+        Name(RESP, ResourceTemplate() {
             Memory32Fixed(ReadOnly,
                 0xFED00000,         // Address Base
                 0x00000400,         // Address Length
                 )
         })
+        Name(RESI, ResourceTemplate() {
+            IRQNoFlags() {2, 8}
+        })
+        Method(_CRS, 0) {
+            Store(\_SB.PCI0.ISA.SMC._STA, Local0)
+            If (LEqual(Local0, 0x0B)) {        // AppleSMC present, add IRQ
+                ConcatenateResTemplate(RESP, RESI, Local1)
+                Return (Local1)
+            } else {
+                Return (RESP)
+            }
+        }
     }
 }