Re: [gentoo-user] Booting Gentoo from USB stick

[J. Roeleveld]

On Thursday 16 September 2010 12:01:43 Jake Moe wrote:
>  On 09/16/10 16:22, J. Roeleveld wrote:
> > On Thursday 16 September 2010 00:34:39 Jake Moe wrote:
> >>  On 16/09/10 08:26, Dale wrote:
> >>> Jake Moe wrote:
> >>>> Thanks for that, I'll rebuild the genkernel with blkid support.
> >>>>
> >>>> As to the second suggestion, there is *no* /dev/sda1 (the partition in
> >>>> question).  It just doesn't exist for some reason.  However, fstab
> >>>> shows that it's mounted, and /sys/block has entries for the disk, so
> >>>> I'm not sure why it's dropped out.  I'm guessing it has something to
> >>>> do with udevd, or uevents?  Because shortly before that, I tell it to
> >>>> find the root partition at /dev/sda1, and it starts to boot, but then
> >>>> it loses it.
> >>>>
> >>>> Jake Moe
> >>>
> >>> The file fstab doesn't show what is mounted.  Either use the command
> >>> "mount" with no options or cat /etc/mtab to see what is actually
> >>> mounted.
> >>>
> >>> Dale
> >>>
> >>> :-)  :-)
> >>
> >> Gah, it's too early.  That's what I meant to say (and previously said in
> >> my original post): when I run "mount", it shows /dev/sda1 is mounted on
> >> /.
> >>
> >> Jake Moe
> >
> > I wonder if it looses the "/dev" tree when it mounts the root-partition
> > read only prior to running the fsck.
> > That could explain why it's not there.
> >
> > Try building a dummy /dev-tree on your root partition with the correct
> > device- nodes hardcoded for /dev/sdxxxxxx and see how far you get then?
> >
> > --
> > Joost
>
> Erm, you've gone a bit beyond my knowledge there.  Are you saying I
> should go into the maintenance console, create a dummy /devdir, and try
> to mknod the hard drive?  I assume I'd use something like 'mknod
> /dev/sda c 8 0'?  If not, what do you mean, cause you've lost me.
>
> Jake Moe

Ok, what I mean is that I think the following might happen:

1) root-dir from ramdisk is mounted under /
2) dev-tree is mounted under /dev
3) /dev/sda1 is mounted under /
4) at this point, /dev might no longer be accessible.

Now, if you make sure that on the USB-root (/dev/sda1) the folder /dev is 
actually populated, then it might continue through the boot-process.

Or, as you mentioned, issue "mknod ......."  commands while in that 
maintenance console, then it might be able to find the /dev/sda, /dev/sda1,... 
devices and continue.

Please bear in mind, I have not actually used nor needed a ramdisk to boot 
from ever since I started using Gentoo.
Not even when I played with booting from USB-sticks myself.
I simply build the kernel with all the necessary drivers compiled-in and used 
that to boot from.

This might also be an idea for you?

--
Joost

Eg. if you do the mknod-commands to build the /dev/sda, /dev/sda1,.... device 
nodes, then it should be able to continue.