Subject: Re: Extending config(8) to allow different root fs types
To: 'Chris G Demetriou' <>
From: Martin Husemann <>
List: tech-kern
Date: 11/03/1996 06:06:05
Chris G Demetriou wrote:

> Actually, that's not really true.  The firmware _us_ supposed to pass
> an indicator of the boot device name on to the kernel, and in fact
> it's the same indicator that the boot blocks use to load the kernel!

True, but it's wrong (or at least misleading) in the situation I described
(booting from CD): it would indicate either fd0 when using a real boot
floppy or would tell "first hard disk" when booting directly from CD,
as the BIOS sets up a virtual ram disk from an image on the CD marked
as the boot image. Neither would give any hint to the CD I realy would
like root to be mounted from. Anyway, that's just a i386 specific problem
we can ignore for now.

> So, let's just ignore the fact that one _really_ shouldn't have to
> specify swap partitions in the config file...  8-)


> i'd say that the syntax should be something more like:

> 	config netbsd root on wd0 fstype ffs

> or, leave out that 'fstype ffs', and it does the 'try a bunch of file
> system types and do the right thing' thing.

> Alternately, something like "root on wd0:ffs" might make sense
> instead, and avoids adding a config keyword.

I don't care about the syntax, as long as I can express what I want.

> Unfortunately, the way root is currently mounted is not conducive to
> these kinds of changes.  These changes are on my "medium-length list"
> and i'm gonig to get to them eventually, but it's not quite trivial.

True. And if/when we change it, could we support yet another extension?
For installation CDs it would be realy cool (tm) if they could figure
the root device from a list of possible devices/partitions. Something like

config netbsd root on cd0:cd9660 or mcd0:cd9660 or acd0:cd9660 swap on wd0 and sd0

and it would use the first fs available from the given list.