lilo: cannot open root device (on usb harddisk)

[Al_]

Hi
I try to install linux (ubuntu lucid) on an external usb harddisk. As the laptop can boot from an USB flash stick, but not from a USB harddisk (500 GB Lacie rikiki), I try to install lilo bootloader and kernel on a USB flash stick, but use the USB harddisk as root. I run lilo to install the bootloader on another machine (desktop with Ubuntu lucid) with the USB flash stick and USB harddisk recognized as /dev/sdf (mounted in /media/LILO) and /dev/sdg, respectively.

The laptop shows the lilo boot menu, then boots, but ends with kernel panic:

...
md: autorun DONE.
VFS: Cannot open root device "UUID=7ba4..." or unknown-block(0,0)
Please append a correct "root=" boot option; here are the available partitions:
0b00 1048575 sr0 driver: sr
Kernel panic - not syncing: VFS: Unable to mount root fs on onknown-block(0,0)
Pid: 1, comm: swapper Not tainted 2.6.32.25-generic #44-Ubuntu
...
The UUID is correct for the first partition of the USB harddisk.
My own thoughts:
- the kernel can not load a usb harddisk?
- the disk inaccessible option in my lilo.conf is wrong (see bold lines in lilo.conf)?

I appreciate any ideas how to solve this, after I have spent already several days on it.

My lilo.conf file:

# see http://tldp.org/HOWTO/LILO-5.html
#
# Install Lilo on the Master Boot Record of a bootable usb flash drive, e.g., violet competact
boot = /dev/sdf
install = menu
# The installer will build the following file. It tells the boot-loader where the blocks of the kernels are.
map = /media/LILO/map
compact
prompt
disk=/dev/sdg
inaccessible
#timeout = 100
# try to use geometric instead of lba32 addressing. Errors should be reported at boot-config time (not at boot time)
# no, geomteric does not work
#geometric
lba32
# The kernel is stored where BIOS can see it.
image = /media/LILO/vmlinuz
append="acpi=off pci=noacpi noapic nolapic pnpbios, pci=usepirqmask, pci=biosirq"
# Lilo tells the kernel to mount the following partition as root. BIOS does not have to be able to see it.
root="UUID=7ba4b03b-6496-4050-8ce8-7855630337d6"
read-onlyHardware info:
laptop = hp / compaq 6910p
USB harddisk: Lacie rikiki 500 GB, ext4 formatted (plus a few GB swap at the upper end)
USB flash: old, noname 256 MB stick, ext2 formatted

[oldfred]

I am not sure lilo has been updated to see ext4 partitions. If you can boot a USB I would think you can boot a external drive? My system showed USB boots none of which worked for a flash drive but then I found the flash drive was actually listed under hard drives.

You can do the same thing with a dedicated /grub or /boot partition.

Herman has info on both grub & grub2 partitions
http://members.iinet.net/~herman546/p20/GRUB2%20Bash%20Commands.html#Dedicated_GRUB_Partit ion
Chainbooting grub2, install to partition & Make CD or floppy - saikee
http://www.justlinux.com/forum/showthread.php?threadid=152790
Herman on separate grub partition:
http://ubuntuforums.org/showthread.php?t=1320270
Grub partition slakkie
http://blog.opperschaap.net/2009/11/13/all-your-grub-are-belong-to-us/
grub2 partition
http://rxezlqu.wordpress.com/2010/04/07/separate-boot-partition-vs-dedicated-boot-partition/

Grub2 partition discussion:
http://ubuntuforums.org/showthread.php?t=1465772

[Al_]

@oldfred: Thanks for your reply. I am also surprised that the system boots from USB flash drive (I tried several, all work; including a 16 GB stick on which I could install entire Ubuntu) but not from the USB harddisk. I have no other USB harddisk, so I can not check whether it is something peculiar to this drive or a general 'feature'. Of course I confirmed that the harddisk can be mounted in a running system, Ubuntu Desktop as well as Windows XP. The latter on the same laptop where I want to boot Linux (I can not use the Win XP harddisk as boot device as it is a corporate laptop with a fully encrypted harddisk that is not even seen from a LiveCD).

I had also tried GRUB previously, with no success. I tried to have /boot on the USB stick and / (root) on the USB harddisk. The best I got was a grub rescue> prompt. So, ending up at a lilo boot menu is already a small success ... Nevertheless, I will look up the links you provided and give GRUB another try.

[Al_]

So, I re-tried GRUB. Thanks to the very clear instructions in the links provided by oldfred (notably http://members.iinet.net/~herman546/p20/GRUB2%20Bash%20Commands.html#GRUB_USB (http://members.iinet.net/%7Eherman546/p20/GRUB2%20Bash%20Commands.html#GRUB_USB)), I created a GRUB2 boot USB flash stick (commandline only) and get a grub prompt. But then I am stuck again, similar to the lilo attempts.

grub> ls
(hd0) (hd0,1) (hd1) (hd1,1)
grub> ls (hd0)
Device hd0: Partition table
grub> ls (hd0,1)
Partition hd0,1: Filesystem type ext2 - Label "GRUB2" - Last modification time 2010-10-10 08:14:20 Sunday, UUID 8d346542-...
grub> ls (hd1)
Device hd1: Partition table
grub> ls hd(1,1)
Partition hd1,1: Unknown filesystemhd0 is the USB flash stick with the grub2 boot installation. hd1 is the internal harddisk, fully encrypted by ProtectDrive, so the partition is not recognizable (it is ntfs); I know it is the internal drive as the laptop LED flashes briefly when entering ls hd(1) or ls hd(1,1). The LED on the USB flash stick flashes with ls (hd0) and ls (hd0,1). The LED on the external USB harddisk is steady on at all times, never flashes. My conclusion: GRUB2 and the BIOS do not see the USB harddisk at all. Possibly I need to load some modules using insmod, but which modules?

[Al_]

Finally, it works :P. This is how I did it, in case anybody else has the same issues (steps 4 - 12 are not needed, just for me to test; the on-screen messages in step 8 allowed me an estimated guess, which device the root on my USB harddisk is, ie., /dev/sdb1).


copied vmlinuz-2.6.32-21-generic and initrd.img-2.6.32-21-generic from the USB harddisk to the top directory of the USB flash stick (renamed for convenience to vmlinuz and initrd.img); for testing purpose, also copied memtest86+.bin to that top directory
connect USB harddisk and USB flash stick to laptop and power on
hit BIOS startup option key to start from USB (in my case F9)
--> a grub prompt appears
to test:
grub> linux16 memtest86+.bin
grub> boot
--> memtest starts
to boot to busy box: reboot, then
grub> linux (hd0,1)/vmlinuz
grub> initrd (hd0,1)/initrd.img
grub> boot
--> (initramfs) busy box prompt appears, as no root for linux was specified
(initramfs) mkdir rikiki
(initramfs) mount -t ext4 /dev/sdb1 rikiki
[ 517.722124] EXT4-fs (sdb1): mounter filesystem with ordered data mode
(initramfs) cd rikiki
(initramfs) ls
--> files and directories in root of USB harddisk are listed!!
to boot really: reboot, then
grub> linux (hd0,1)/vmlinuz root=/dev/sdb1 ro quiet splash
grub> initrd (hd0,1)/initrd.img
grub> boot

What is left to do: a small grub.cfg to automate steps 13 - 15.

[oldfred]

Herman has in his link how to create a grub.cfg. When I created a grub.cfg for loop mounting the ISO on a USB, I just created a file and copied into it some stanza.

You will need something like this.

This uses the links from a standard install, but it looks like you renamed your kernels to the same name? Standard installs have a updated link in / (root) to the kernels in /boot so you do not have to have the exact version numbers if you use the link.

Boot most up2date kernel on sda1:

menuentry "Desktop sda1" {
set root=(hd0,1)
linux /vmlinuz root=/dev/sda1 ro quiet splash
initrd /initrd.img
}


I like to use spacer (blank menu entry), reboot & Halt as extra options.
menuentry " " {
set root=
}

menuentry "Reboot" {
reboot
}

menuentry "Halt" {
halt
}

[Al_]

I was out of town for a few days; now back at Linux.

Rename versus symbolic link: good point. I followed your advice (and Ubuntu standard, as I have meanwhile realized), moved kernel and initrd.img to /boot, and use symbolic links with short names in /.

Re grub.cfg, still to be done. Should be fairly straight forward in /etc/grub.d/40_custom.

Thanks again for your help.

Al_