Can't get LFS6.7 to boot

PJB3589 · 01-28-2011, 07:27 PM

Hello,

Just finished building an LFS 6.7 system. When I reboot it, I get tossed to the grub rescue prompt with an error of file not found. When I run the set command, I get the following:

Code:

prefix=(hd0,0)/boot/grub
root=hd0,1

This is incorrect. My LFS system is on the partition hd1,1. If I look in the grub.cfg file, this is specified correctly. So why is it wrong when I reboot?

If I manually set the prefix and root to the correct partition, I am able to start booting LFS. However, I get a kernel panic of:

Code:

kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)

Any ideas?

Thanks

druuna · 01-29-2011, 04:20 AM

Hi,

Could you post the following information:

- Content of $LFS (and, if you decided to create it as a mount point, $LFS/boot)
- Your /etc/fstab file,
- Relevant menu entry from /boot/grub/grun.cfg.

Are you doing this while still running from the host OS (chap. 8.4.3) or after finishing chap. 8.4.4?

You do know that grub and grub2 have a difference in numbering when pointing to devices?
For example if you used /dev/sda3 its notation would be:
- Grub -> hd0,2
- Grub2 -> hd0,3

You mention hd1,1, which grub2 translates to: /dev/sdb1

The kernel panic message might be related to the above, so I'm not going into that yet.

Hope this helps.

PJB3589 · 01-31-2011, 01:17 PM

My LFS partition is on /dev/sdb1. This is after 8.4.4.

Contents of /etc/fstab:

Code:

root:/sources# cat /etc/fstab
# Begin /etc/fstab

# file system  mount-point  type   options         dump  fsck
#                                                        order

/dev/sdb1     /            ext2  defaults        1     1
#/dev/sda2     swap         swap   pri=1           0     0
proc           /proc        proc   defaults        0     0
sysfs          /sys         sysfs  defaults        0     0
devpts         /dev/pts     devpts gid=4,mode=620  0     0
tmpfs          /dev/shm     tmpfs  defaults        0     0
# End /etc/fstab

GRUB menu entry:

Code:

### BEGIN /etc/grub.d/10_linux ###
menuentry "GNU/Linux, with Linux 2.6.37-lfs-6.7" --class gnu-linux --class gnu --class os {
        insmod ext2
        set root='(hd1,1)'
        search --no-floppy --fs-uuid --set 95537638-04e2-433d-b1f5-b23d33ffe716
        echo    Loading Linux 2.6.37-lfs-6.7 ...
        linux   /boot/vmlinux-2.6.37-lfs-6.7 root=/dev/sdb1 ro  
}
menuentry "GNU/Linux, with Linux 2.6.37-lfs-6.7 (recovery mode)" --class gnu-linux --class gnu --class os {
        insmod ext2
        set root='(hd1,1)'
        search --no-floppy --fs-uuid --set 95537638-04e2-433d-b1f5-b23d33ffe716
        echo    Loading Linux 2.6.37-lfs-6.7 ...
        linux   /boot/vmlinux-2.6.37-lfs-6.7 root=/dev/sdb1 ro single 
}
### END /etc/grub.d/10_linux ###

druuna · 01-31-2011, 01:42 PM

Hi,

The /etc/fstab file looks ok.

You posted the wrong grub file. You need to look at this one: /boot/grub/grub.cfg

Which command did you execute in chapter 8.4.4? And are you sure you want to override your current boot-loader?

PJB3589 · 01-31-2011, 04:05 PM

That menu entry is from my /boot/grub/grub.cfg file.

I'm building LFS in a VM, so I did overwrite my boot loader as I have a snapshot prior to running the "grub-setup /dev/sda" command.

crts · 01-31-2011, 06:53 PM

Hi,

did you compile your kernel with the ext2 module? I once compiled it with the default options and the ext2 module was not in it. The system also would not boot up. I do not recall the exact error message. Boot into your host, remount your LFS partition and issue the following

Code:

grep 'EXT2' $LFS/boot/config-2.6*

If the output is something like

Code:

#CONFIG_EXT2_FS is not set

Then you will have to recompile your kernel - partly at least.

PJB3589 · 02-02-2011, 09:04 AM

Actually, that's a mistake. The partition LFS is on is ext3. I corrected /etc/fstab, but I still have the same problem.