Skip site navigation (1)Skip section navigation (2)
Date:      Thu, 29 Apr 1999 14:01:07 -0600 (MDT)
From:      "Kenneth D. Merry" <ken@plutotech.com>
To:        spork@super-g.com (spork)
Cc:        freebsd-scsi@FreeBSD.ORG
Subject:   Re: device assignment
Message-ID:  <199904292001.OAA78007@panzer.plutotech.com>
In-Reply-To: <Pine.BSF.4.00.9904291544200.17568-100000@super-g.inch.com> from spork at "Apr 29, 1999  3:50:10 pm"

next in thread | previous in thread | raw e-mail | index | archive | help
spork wrote...
> Hi,
> 
> I have two scsi controllers, a built-in 7890 and a 2940-U2W.  When I
> installed, bios drive "0" and da0 were at ID 0 of the 7890 controller, so
> the boot process and the root filesystem were both on the potentially
> buggy 7890.

Both of those controllers have 7890's on board...

> To see if I could fix the problem by booting from the 2940-U2W, I swapped
> the drives from one controller to the other and told the BIOS that the
> 7890 should *not* be the boot device.  ahc0 is the 7890 and ahc1 is the
> 2940 card.
> 
> So it does now boot from that drive, but when it goes to mount root, it
> wants to mount the first device on ahc0, which is another drive.
> 
> What determines the device mappings here?  Can I fix this or must I
> reinstall?  Why does the built-in controller always get ahc0 instead of
> ahc1?

FreeBSD's device assignment is generally determined by probe order.  PCI
devices are probed in ascending order, regardless of what order the BIOS
probes things in.  (Note that the probe order is a bit different now in
-current for machines with more than one PCI bus.  Doug Rabson said that
he's planning on writing code that will at least allow the old probing
behavior.)

You need to do the following in the loader to get things to work, assuming
that the drive you want to boot off of is "da1":

set root_disk_unit=1

Then in your fstab, make sure that your root filesystem, etc., reference
da1, not da0.

Ken
-- 
Kenneth Merry
ken@plutotech.com


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-scsi" in the body of the message




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199904292001.OAA78007>