FreeBSD 8.0 hangs on boot with ACPI enabled

[Dana Myers]

John Baldwin wrote:
> No, when ACPI is enabled the BAR is getting reset to 0 for some reason 
> after
> the boot has started and FreeBSD tries to guess at an address to use.  
> Unfortunately it picks an address that doesn't work.  This is fixable, it's 
> just part of the much larger PCI resource management problem.
>
> OTOH, I'm not sure why initializing ACPI is trashing the BAR.  If you want, 
> you can try to narrow down at what point the BAR gets reset to 0
I'm sure it's a side-effect of switching into ACPI mode.
The Solaris port of ACPI CA has an option to leave the
system in legacy mode during ACPI initialization which I've
used to diagnose several instances of PCI config space
being trampled by the ACPI-mode switch (done by SMM
BIOS code).  Sometimes an update to the BIOS solves
the problem, but usually not.  My guess is that Windows
reconfigures PCI devices after switching into ACPI
mode, and thus avoids this class of BIOS bug.

Dana
dana.myers at gmail.com