VirtualBox default VMs expose an AC'97 audio controller (8086:2415,
class 04/subclass 01) whose BAR0 is an I/O-space BAR. The IntelHDA
driver matched any Intel multimedia subclass, and ReadBar0 masked the
I/O BAR's port number into a bogus 'physical address' that MapMMIO
panicked on (non-page-aligned), halting boot.
Two fixes:
- IntelHDA now matches only subclass 0x03 (HD Audio); AC'97 (0x01) is
a different programming model and is not claimed.
- ReadBar0 returns 0 (no usable MMIO BAR) for I/O-space BARs instead
of handing a port number to MapMMIO.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
daniel
