Boot failure with r272146

With r272146 my SATA controller fails to attach, preventing the kernel
from mounting root.  I've attached a log of as much as dconschat would
allow.  The relevant portion is pcib10:

atapci0: <ServerWorks K2 SATA150 controller> mem 0xfa402000-0xfa403fff
at device 12.0 on pci10 pcib1: failed to reserve resource for pcib10
pcib10: failed to allocate initial I/O port window (0-0xffffffff,0x10)
atapci0: 0x10 bytes of rid 0x20 res 4 failed (0, 0xffffffffffffffff).
atapci0: unable to map interrupt
device_attach: atapci0 attach returned 6

pcib10: allocated memory range (0xfa400000-0xfa400fff) for rid 10 of
pci1:3:14:0 atapci0: <ServerWorks K2 SATA150 controller> mem
0xfa402000-0xfa403fff at device 12.0 on pci10 pcib1: failed to reserve
resource for pcib10 pcib10: failed to allocate initial I/O port window
(0-0xffffffff,0x10) atapci0: 0x10 bytes of rid 0x20 res 4 failed (0,
0xffffffffffffffff). atapci0: unable to map interrupt
device_attach: atapci0 attach returned 6
ata0: <Shasta Kauai ATA Controller> mem 0xfa404000-0xfa407fff at device
13.0 on pci10 ofw_pci mapdev: start fa404000, len 16384
ata0: unable to allocate interrupt
device_attach: ata0 attach returned 6


It works fine with r271697 kernel (latest I have booting).  I haven't
yet tried bisecting.

Hardware is a PowerMac G5 (last generation).

- Justin