Subject: Re: how can I put swap on more than 1 disk
To: None <amiga@NetBSD.ORG>
From: Michael L. Hitch <firstname.lastname@example.org>
Date: 04/27/1995 13:45:38
On Apr 27, 3:21pm, David Jones wrote:
> > I've wondered exactly what the GENERIC option is myself. The
> > GRNERIC config says "mini-root boot support". Is mini-root the same as
> > single-user, or is it the ability to select a root device (with the -b
> > option)?
> A miniroot is a small root filesystem that is installed in your swap
> partition. You then boot from that, and use it to install the real root.
> That's what SunOS does.
> In the kernel, if you have booted from sdXb, then you need to offset the
> start of swap space by the size of the miniroot so you don't page all over
> your root filesystem.
It almost works in NetBSD with one slight (!) problem. Because the root
and swap are using the same device, the swap initialization fails because
the root file system has already has the device open. Adding a check to
ignore the EBUSY error if the swap device is the same as the root device
allows the mini-root to work.
This also gives an alternate way to install the system without needing
to use the floppy drive. I've copied the install filesystem image to
the swap partition (using dcp on AmigaDOS), loaded NetBSD with the -b
option, and specified sd0* as the root device. The '*' indicates that
the root is on the swap device. With the patch to fix the swap device
open failure, it appears to work (I've gotten to the point of running the
This also has the advantage of allowing a larger filesystem image
for the install. The current image does not fit onto an 880K floppy
anymore. The current kernel will reserve 2MB of the swap partition for
the root, which is plenty for an install.
Michael L. Hitch INTERNET: email@example.com
Office of Systems and Computing Services
Montana State University Bozeman, MT USA