6.0 BETA3 reboot hangs on SMP system if BIOS USB disabled

[M. Warner Losh]

In message: <200508301422.46354.jhb at FreeBSD.org>
            John Baldwin <jhb at FreeBSD.org> writes:
: On Monday 29 August 2005 08:51 pm, Mark Kirkwood wrote:
: > John Baldwin wrote:
: > > Ok, your BIOS is being a PITA. :)  First off, can you try setting
: > > 'hw.pci.enable_io_modes=0' from the loader and seeing if that fixes the
: > > problem?
: >
: > Sure does, thanks for looking at this!
: 
: Ok, don't go away. :)  Warner or I can work on a patch to fix this then that 
: won't require you to set that tunable.

I think that might be very hard to do that.

While some (bogus) BIOSes set the maps to be all f's for devices they
have disabled, many devices default to this value on power up.  Since
we have to perform lazy resource assignment for these devices, it may
be difficult to differentiate between the unassigned case and the
disabled case.  Is there something I'm missing as to how we can tell
the difference between these two cases?

Warner