Subject: Re: grub "Error 2"?
To: Manuel Bouyer <bouyer@antioche.eu.org>
From: Johan Ihren <johani@johani.org>
List: port-xen
Date: 04/11/2007 20:27:02
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

>> "GRUB loading, please wait"
>>
>> followed by:
>>
>> "Error 2"
>>
>> and no further action. This last message looks suspiciously like an
>> error message from the NetBSD bootloader, but I have no idea why that
>> would be.
>>
>> Note that (a) this is with a single large (80GB) root partition
>> (which works just fine for me on at least four other systems)
>
> Yes, it can work. It depends on where the kernels (and I guess grub
> files ) are located on disk. Do a fresh install and immediatly install
> xen kernels and grub, it may work because FFS will allocate blocks  
> near
> the beggining of the disk: ffs tries to allocates inodes near the
> parent's inode, and blocks near the inode. / has inode 2, so  
> everything in
> / or /grub will not be far away at this stage.
> start working, install packages, etc ... the first cylinder groups  
> will
> fill up. intall a new kernel in / (either a new inode, or  
> overwriting an
> existing inode with a larger file), there's no free blocks in the  
> first
> cylinder groups and your file ends up with blocks away from the  
> beggining
> of disk. And grub can't load it.
>
> Now if you do some filesystem activity before setting up grub, it's  
> possible
> that /grub itself is too far from the start of disk and can't be  
> loaded
> by the first stage grub.
>
> So: never make a FFS larger than 512Mo if you want it to play well  
> with
> grub.

Thanks, Manuel. Point taken. Is it also important to play with the  
blocksize and frag size or is that unnecessary as long as the root  
file system isn't too big?

>> and (b)
>> I wonder a bit what the "e" in "grub> root (hd0,e)" in the Xen guide
>> refers to?
>
> partition e in NetBSD disklabel of disk hd0. That's because on this  
> system
> I had several NetBSD installations, and the Xen one used partition e.

Aha, I see (and I figured out that I wanted (hd0,a) through trial and  
error) I suggest the guide is updated with "root (hd0,a)" instead, as  
that's a more typical configuration.

Regards,

Johan

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.5 (Darwin)

iD8DBQFGHSh4KJmr+nqSTbYRAlWCAJ9e+lTy39Sb+f6/7qZmtAqUhsAJMgCdFq69
DRGY7dayhr5EM39cpf+DZE8=
=rWtI
-----END PGP SIGNATURE-----