-BETA2 and Thunder K8WE

I just tried booting 6.0-BETA2 on a Tyan Thunder K8WE, to no success.
Even with the on-board SCSI disabled, the system hangs after probing mpt0:
it does the SCSI device settle delay[1], picks up the SATA drives, then
hangs.  Under a 'boot -v', I get a whole bunch of cruft about detecting
devices on mpt0.  The system fully freezes after it's done, though, so I
can't really pull much data from the dmesg.

I've tried booting with and without SCSI enabled, to the same effect.  I
haven't yet tried booting without ACPI, as the last time I tried that, the
system didn't pick up any drives at all.

  - Damian

[0] Which, strangely, happens before the SATA detection.  In 5.3, the settle
delay definitely happens after the SATA detection.