[lfs-support] Cannot boot into LFS install

Ken Moffat zarniwhoop at ntlworld.com
Fri Jan 25 18:28:24 PST 2013


On Fri, Jan 25, 2013 at 08:18:45PM -0500, matthew gruda wrote:
> Oops, pressed the wrong button.  Anyway, i used "update-grub" from the host
> system and it detected the LFS install and got this output:
> Generating grub.cfg ...
> Found background: /boot/desktop-grub.png
> Found background image: /boot/desktop-grub.png
> Found linux image: /boot/vmlinuz-3.2.0-36-generic
> Found initrd image: /boot/initrd.img-3.2.0-36-generic
> Found linux image: /boot/vmlinuz-3.2.0-34-generic
> Found initrd image: /boot/initrd.img-3.2.0-34-generic
> Found memtest86+ image: /boot/memtest86+.bin
> Found Linux From Scratch (7.2) on /dev/sda1
> Found Ubuntu 11.10 (11.10) on /dev/sda2
> done
 It doesn't seem to have found a vmlinuz from LFS
> 
> then, I rebooted into the LFS install and got this error upon booting:
> VFS: Cannot open root device "sda1" or unknown-block(0,0) error -6
> ...
> Kernel Panic - not syncing unable to mount root fs on unknown-block(0,0)
> 

 which means drivers for your disk controller(s) or for your root
filesystem were not found, perhaps because it is somehow using an
ubuntu kernel where all of these things are in the initrd.

 I'm surprised that LFS is on the first primary partition with
ubuntu on the second, but I imagine that is how you set it up before
you installed ubuntu.

> On Fri, Jan 25, 2013 at 8:13 PM, matthew gruda <matthewgruda at gmail.com>wrote:
> 
> > I installed LFS next to an existing Ubuntu installation.  The Ubuntu
> > install put /boot on the same partition as the rest of the os.  I
> > successfully compiled and installed all the packages, and used
> >
> >

 We usually moan about top-posting here, but I've left this for
context.  The last time I installed an LFS-like system alongside
debian [ on ppc ] I copied the kernels to wherever the distro had
put its own kernels.  And then I edited the bootloader config by
hand.

 For update-grub, at least in grub2, the kernel has to be called
vmlinuz-something.  I assume, perhaps wrongly, that update-grub will
create all sorts of weird and stupid combinations for what it finds
(e.g. ubuntu kernel for LFS system).

 People here mostly avoid update-grub and edit grub.cfg.  I expect
you can fix this by editing that file n ubuntu [ it's probably set to
be read-only, perhaps only for root ] to ensure that for the LFS
system it uses the correct kernel and does not reference an initrd.

 Once that is working (possibly, you may also need to rebuild your
kernel if you didn't include the necessary drivers and kept them as
modules), you should save details of what is in the LFS entr{y,ies}
so you can restore them if you ever let ubuntu update its kernel.

 I think someone offered a suggestion of how to set up the files so
that update-grub would handle an LFS install, probably in the last 6
months, but since the list archives are offline at the moment I
can't suggest where to search.

ĸen
-- 
das eine Mal als Tragödie, das andere Mal als Farce



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