I wrote:
> Ouch.  I decided that my trusty no-name Pentium 133 tower server should be
> my test mule for my 1.2.1 -> 1.3.1 upgrade (SPARCstation next), so I set
> off to do it.

[tale of woe elided]

> The Pentium has an Adaptec 3940W SCSI controller with two channels; there
> is one internal 2.1 Gb disk on channel A, and an external HP ScanJet IIc
> also on channel A.  In later tests I removed the scanner from the bus, so
> it's not relevant here.
> 
> I booted the 1.3.1 install floppy and told "sysinst" I wanted to do an
> Upgrade.
> 
> It fsck'ed the disks OK, then as soon as it got to the point where it says
> 
> 	Populating filesystems with bootstrapping binaries and config files...
> 
> the system locked up hard.  Disk drive (and front panel "Disk" LED) stuck on,
> solid.  :-(

Update: the same exact phenomenon occured with the 1.3 install floppy.  Sigh.

So what changed in the ahc driver between 1.2.1 and 1.3 that locks up my
system so solidly?  Arggh.  (And the differences between the 1.2.1 and 1.3.1
/usr/src/sys/dev/pci/ahc_pci.c look almost mostly cosmetic, to boot.)

	- Greg