Arch Linux

williumbillium

Member

Registered: 2009-02-22

Posts: 3

[solved] can't boot custom kernel: root fs cannot be detected

I compiled a kernel for the first time and followed this guide:

http://wiki.archlinux.org/index.php/Ker … sers_Guide

When I boot I get an error similar to the following:

ERROR: Failed to parse block device name for '/dev/disk/by-uuid/5b2ac1ca-5790-45f5-b00f-4f1323c285e7' unknown
ERROR: root fs cannot be detected. Try using the rootfstype= kernel parameter.
Waiting for devices to settle...done.

Root device '/dev/disk/by-uuid/5b2ac1ca-5790-45f5-b00f-4f1323c285e7' doesn't exist, attempting to create it

ERROR: Failed to pars block device name for '/dev/disk/by-uuid/5b2ac1ca-5790-45f5-b00f-4f1323c285e7'
ERROR: Unable to create/detect root device '/dev/disk/by-uuid/5b2ac1ca-5790-45f5-b00f-4f1323c285e7'
Dropping recovery shell... type 'exit' to reboot
NOTE: klibc contains no 'ls' binary, use 'echo *' instead

If device '/dev/disk/by-uuid/5b2ac1ca-5790-45f5-b00f-4f1323c285e7' gets created while you are here, try adding 'rootdelay=8' or higher to the kernel command-line

I am confident that the device is specified correctly in menu.lst as I can still boot with the previous kernel.

/boot/grub/menu.lst (snipped):

# (0) ec patched
title  Arch Linux (ec patched)
root   (hd0,0)
kernel /boot/vmlinuz-2.6.28.7-ARCHMOD root=/dev/disk/by-uuid/5b2ac1ca-5790-45f5-b00f-4f1323c285e7 ro
initrd /boot/kernel26-ARCHMOD.img

# (1) Arch Linux
title  Arch Linux
root   (hd0,0)
kernel /boot/vmlinuz26 root=/dev/disk/by-uuid/5b2ac1ca-5790-45f5-b00f-4f1323c285e7 ro
initrd /boot/kernel26.img

/etc/fstab (snipped):

UUID=2d8e13fd-a03e-45f5-9b76-bf775d238534 swap swap defaults 0 0
UUID=5b2ac1ca-5790-45f5-b00f-4f1323c285e7 / ext4 defaults,noatime 0 1

At this point I believe the problem may be that the ext4 module is missing from initrd.  This is what /etc/mkinitcpio.conf looks like:

# vim:set ft=sh
MODULES=""
BINARIES=""
FILES=""
HOOKS="base udev autodetect pata scsi sata filesystems"

Do I need to specify ext4 explicitly?  Could there be another cause? Thanks.

Last edited by williumbillium (2009-02-22 21:28:19)

fwojciec

Member

Registered: 2007-05-20

Posts: 1,411

Re: [solved] can't boot custom kernel: root fs cannot be detected

Try using regular /dev/sdXX partition notations instead of UUIDs -- my custom kernels don't work with UUIDs, but if you're generating the img file with mkinitcpio they should work, at least in theory (I think the mkinitcpio udev hook is required if you want to use UUIDs).  Just an idea.

smartboyathome

Member

From: $HOME

Registered: 2007-12-23

Posts: 334

Website

Re: [solved] can't boot custom kernel: root fs cannot be detected

Also, try adding "rootfstype=ext4" after "root=" in your GRUB's kernel line, and it should work.

Last edited by smartboyathome (2009-02-22 19:21:05)

williumbillium

Member

Registered: 2009-02-22

Posts: 3

Re: [solved] can't boot custom kernel: root fs cannot be detected

I tried using /dev/sda1 in my menu.lst and the rootfstype=ext4 parameter but no joy.

I think there might be a problem with my config and the kernel modules not getting loaded.  I did an lsmod at the grub prompt and its output was empty.  I'm going to try recompiling now.

methuselah

Member

Registered: 2007-10-02

Posts: 570

Re: [solved] can't boot custom kernel: root fs cannot be detected

Try this AUR package to build a custom kernel: http://aur.archlinux.org/packages.php?ID=23467

R00KIE

Forum Fellow

From: Between a computer and a chair

Registered: 2008-09-14

Posts: 4,734

Re: [solved] can't boot custom kernel: root fs cannot be detected

I have seen that sort of problem when booting from usb, do as fwojciec says, try with sdXX ids and you can also try to add rootdelay=8 (or a larger number) to your kernel line, pass the rootfstype parameter too as smartboyathome says.

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R00KIE
Tm90aGluZyB0byBzZWUgaGVyZSwgbW92ZSBhbG9uZy4K

williumbillium

Member

Registered: 2009-02-22

Posts: 3

Re: [solved] can't boot custom kernel: root fs cannot be detected

OK, I made an elementary mistake (local version name was wrong in menuconfig) and all of the modules were built into a folder with the wrong name under /lib/modules/  I rebuilt everything with the correct local version set and it's working.  Thanks everyone for the suggestions.