Date: Sun, 30 Dec 2001 17:44:20 -0800 From: Mike Smith <msmith@freebsd.org> To: naddy@mips.inka.de (Christian Weisgerber) Cc: freebsd-alpha@freebsd.org Subject: Re: -CURRENT boot1 broken? Message-ID: <200112310144.fBV1iKI01874@mass.dis.org> In-Reply-To: Your message of "Mon, 31 Dec 2001 00:50:20 GMT." <a0ococ$50e$1@kemoauc.mips.inka.de>
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> John Baldwin <jhb@FreeBSD.org> wrote:
>
> > > This suggests that boot1 is broken.
> >
> > Ugh, it shouldn't be. :(
>
> Well, I guess it isn't. When I moved my system to a new disk, I
> created all filesystems with 16384/2048. Pretty useless for the
> root filesystem, I admit, except for consistency's sake. Turns out
> that boot1 doesn't handle this. Jumping through some hoops I have
> moved / back to 8192/1024 and it works fine now. *Sigh*
>
> As a side effect of experimenting with various boot combinations,
> I'm confused about where the different components are loaded from.
> Experimental evidence suggests this:
>
> 1. At the SRM prompt, booting from a particular drive will load the
> bootstrap (boot1) from there.
> 2. boot1 proceeds to load /boot/loader from the same drive. You
> can specify a different file name, but there appears to be no
> way to qualify this with a drive.
Phases 1 and 2 use SRM, which gives you an anonymous "device you booted
from". This is why you can't eg. load drivers from floppy when booting
from CDROM.
> 3. loader pulls in the kernel from da0, even if booted from a
> different drive.
This isn't correct; the loader also uses SRM, and has no way of accessing
anything other than "the device you booted from".
> 4. The kernel mounts da0a as root device.
>
> I'm surprised by the step from any drive (1, 2) to the fixed(?)
> assumption of da0 (3, 4).
There is no way for the kernel to work out what "the device you booted
from" was. The loader reads /etc/fstab and tells the kernel what it
should mount / from based on the contents therof.
I'm not sure what system you were using to get the results in 3 and 4
above, but I don't think it was FreeBSD.
--
... every activity meets with opposition, everyone who acts has his
rivals and unfortunately opponents also. But not because people want
to be opponents, rather because the tasks and relationships force
people to take different points of view. [Dr. Fritz Todt]
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