Rework the APIC mixed mode support a bit:

- Require the APIC enumerators to explicitly enable mixed mode by calling
  ioapic_enable_mixed_mode().  Calling this function tells the apic driver
  that the PC-AT 8259A PICs are present and routable through the first I/O
  APIC via an ExtINT pin.  The mptable enumerator always calls this
  function for now.  The MADT enumerator only enables mixed mode if the
  PC-AT compatability flag is set in the MADT header.
- Allow mixed mode to be enabled or disabled via a 'hw.apic.mixed_mode'
  tunable.  By default this tunable is set to 1 (true).  The kernel option
  NO_MIXED_MODE changes the default to 0 to preserve existing behavior, but
  adding 'hw.apic.mixed_mode=0' to loader.conf achieves the same effect.
- Only use mixed mode to route IRQ 0 if it is both enabled by the APIC
  enumerator and activated by the loader tunable.  Note that both
  conditions must be true, so if the APIC enumerator does not enable mixed
  mode, then you can't set the tunable to try to override the enumerator.

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/i386/acpica/madt.c b/sys/i386/acpica/madt.c
index 81dd058..3bccc4a 100644
--- a/sys/i386/acpica/madt.c
+++ b/sys/i386/acpica/madt.c
@@ -368,6 +368,8 @@ madt_setup_io(void)
 	}
 		    
 	/* First, we run through adding I/O APIC's. */
+	if (madt->PCATCompat)
+		ioapic_enable_mixed_mode();
 	madt_walk_table(madt_parse_apics, NULL);
 
 	/* Second, we run through the table tweaking interrupt sources. */