[lfs-support] Boot Issues

Ken Moffat zarniwhoop at ntlworld.com
Thu Sep 26 18:20:32 PDT 2013


On Thu, Sep 26, 2013 at 05:43:51PM -0400, Casey Daniels wrote:
> Thanks for the info,
>   but followed the instructions and as usual I get the grub rescue 
> prompt which is a total different issue and question.
> 
> But I tried what I have been trying to get the normal boot menu up
> 
> set prefix(hd0,??)
> insmod normal
> normal
> 
> now its saying no such partition.
> I ls at the rescue prompt and it shows the (HD0) but it gives no 
> partitions to go along with it.
> 
 Please don't top post, we hate it.

 You said this was variously a thumb drive and an SD card (you had a
different issue with the real disk).  You also said that you created
an MSDOS partition table, but did you also create partitions, or are
you trying to use the whole of /dev/sdX as a single filesystem ?

 If you do have partitions, then grub _might_ work with
	insmod ext2
	set root='(hd0,msdosN)'
 where N is the partition number containing /boot - and presumably
if /boot isn't a separate partition you would need to point to
/boot/vmlinuz-whichever instead of just vmlinuz (dunno, I always
have a separate /boot partition on my x86 machines).

 That _might_ be enough to solve the grub side of the problem, but
you will still need to do something to let the kernel find the
filesystem whichever "disk" it appears as (typically, use an
initramfs, I believe).  Just in case this isn't clear, the stick or
external drive might be /dev/sdb or /dev/sdc at the moment, but it
could shouw up as /dev/sda even if there is a "real" disk currently
there, it all depends on which appears first and the order is
unreliable across different kernels / different configs.  So the
intramfs has to contain enough of a system to then be able to mount
the stick or external drive, e.g. by UUID (generally, the kernel
doesn't understand UUIDs although the situation on GPT drives is, I
think, slightly different).  But I don't have experience in booting
from removable drives/sticks.

 I suggest that you change your plans:

1. Get it to boot on the spinning-rust /dev/sda.  That will allow
you to prove that the completed system is usable.  If you can't get
this to work, please report the error(s) in detail, along with your
partitioning.  You WILL also need a rescue CD in case things become
broken.

2. Study the various posts which google finds about booting to a
removable disk / memory stick.  There are a number of different (and
probably incompatible) solutions.  In particular, look at the 'About
initramfs' page in BLFS :
http://www.linuxfromscratch.org/blfs/view/svn/postlfs/initramfs.html
although that doesn't specifically talk about booting from external
usb drives.

http://www.linuxquestions.org/questions/linux-from-scratch-13/booting-lfs-from-usb-stick-897465/
might have something useful in it (for the grub suggestions).  There
have been many threads here over the years, but the mail archives
aren't available so I can no longer point you to them.

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



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