kernel panic when trying to load PCLinuxOS, bootloader configuration

[LarryO61]

Hello:
As explained earlier, I am trying to have a triple boot system with Windows Vista, Mint Linux and PCLinuxOS. My bootloader is GRUB2. When loading PCLinuxOS, which is on sdb1-6, I get the kernel panic message "VFS cannot open root device. UUID=XXXXXXXX. VFS: Unable to mount root fs on unknown block (0,0)."

I would like to add a stanza to the Grub2 bootloader to recognize PCLinuxOS. Any suggestions in what to include in the stanza?
Thanks,
Larry
P.S.

here is what I get when I run update-grub

Found Debian background: linuxmint.png
Found linux image: /boot/vmlinuz-2.6.35-22-generic-pae
Found initrd image: /boot/initrd.img-2.6.35-22-generic-pae
Found memtest86+ image: /boot/memtest86+.bin
Found Windows Vista (loader) on /dev/sda1
Found PCLinuxOS on /dev/sdb1


Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x1549f232

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1       47195   379085200+   7  HPFS/NTFS
/dev/sda2           47195       60802   109298689    5  Extended
/dev/sda5           47195       60802   109298688   83  Linux

Disk /dev/sdb: 200.0 GB, 200049647616 bytes
255 heads, 63 sectors/track, 24321 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xa4f26f28

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1        1568    12594928+  83  Linux
/dev/sdb2            1569       24321   182763442    5  Extended
/dev/sdb5            1569        2077     4088511   82  Linux swap / Solaris
/dev/sdb6            2078       24321   178674898+  83  Linux

[uncleV]

Hi and welcome!

This is an issue of GRUB2 silly fault well known in the forum. There are some threads on it in this section.

Find them or post here the content of your boot/grub/grub.cfg file (the bootloader of GRUB2 by which you are booting) to specify where you should edit to hd(m, n+1)  

[LarryO61]

Here is the contents of my Grub2 config file: The last three entries are PCLinuxOS, which is on an external drive.


# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
  set have_grubenv=true
  load_env
fi
set default="5"
if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}

function recordfail {
  set recordfail=1
  if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}

function load_video {
  insmod vbe
  insmod vga
}

insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 746220f8-ce51-4e62-8ec6-7d8343f91220
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=1280x1024
  load_video
  insmod gfxterm
fi
terminal_output gfxterm
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 746220f8-ce51-4e62-8ec6-7d8343f91220
set locale_dir=($root)/boot/grub/locale
set lang=en
insmod gettext
if [ "${recordfail}" = 1 ]; then
  set timeout=-1
else
  set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 746220f8-ce51-4e62-8ec6-7d8343f91220
insmod tga
if background_image /usr/share/images/grub/Moraine_Lake_17092005.tga ; then
  set color_normal=black/black
  set color_highlight=magenta/black
else
  set menu_color_normal=white/black
  set menu_color_highlight=black/light-gray
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/06_mint_theme ###
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 746220f8-ce51-4e62-8ec6-7d8343f91220
insmod png
if background_image /boot/grub/linuxmint.png ; then
  set color_normal=white/black
  set color_highlight=white/light-gray
else
  set menu_color_normal=white/black
  set menu_color_highlight=white/light-gray
fi
### END /etc/grub.d/06_mint_theme ###

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Linux Mint 10, 2.6.35-22-generic-pae (/dev/sda5)' --class linuxmint --class gnu-linux --class gnu --class os {
   recordfail
   insmod part_msdos
   insmod ext2
   set root='(hd0,msdos5)'
   search --no-floppy --fs-uuid --set 746220f8-ce51-4e62-8ec6-7d8343f91220
   linux   /boot/vmlinuz-2.6.35-22-generic-pae root=UUID=746220f8-ce51-4e62-8ec6-7d8343f91220 ro  splash vga=794  quiet splash
   initrd   /boot/initrd.img-2.6.35-22-generic-pae
}
menuentry 'Linux Mint 10, 2.6.35-22-generic-pae (/dev/sda5) -- recovery mode' --class linuxmint --class gnu-linux --class gnu --class os {
   recordfail
   insmod part_msdos
   insmod ext2
   set root='(hd0,msdos5)'
   search --no-floppy --fs-uuid --set 746220f8-ce51-4e62-8ec6-7d8343f91220
   echo   'Loading Linux 2.6.35-22-generic-pae ...'
   linux   /boot/vmlinuz-2.6.35-22-generic-pae root=UUID=746220f8-ce51-4e62-8ec6-7d8343f91220 ro single  splash vga=794
   echo   'Loading initial ramdisk ...'
   initrd   /boot/initrd.img-2.6.35-22-generic-pae
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/10_lupin ###
### END /etc/grub.d/10_lupin ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
   insmod part_msdos
   insmod ext2
   set root='(hd0,msdos5)'
   search --no-floppy --fs-uuid --set 746220f8-ce51-4e62-8ec6-7d8343f91220
   linux16   /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
   insmod part_msdos
   insmod ext2
   set root='(hd0,msdos5)'
   search --no-floppy --fs-uuid --set 746220f8-ce51-4e62-8ec6-7d8343f91220
   linux16   /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
menuentry "Windows Vista (loader) (on /dev/sda1)" {
   insmod part_msdos
   insmod ntfs
   set root='(hd0,msdos1)'
   search --no-floppy --fs-uuid --set 6a8c5e178c5dde5f
   chainloader +1
}
menuentry "linux (on /dev/sdb1)" {
   insmod part_msdos
   insmod ext2
   set root='(hd1,msdos1)'
   search --no-floppy --fs-uuid --set 0f25c9d8-de98-4a8d-aa3b-5fb3eb5ef615
   linux /boot/vmlinuz BOOT_IMAGE=linux root=UUID=0f25c9d8-de98-4a8d-aa3b-5fb3eb5ef615 resume=UUID=ba96f397-96ee-44cb-9118-eae677f3969c splash=silent vga=788
   initrd (hd0,0)/boot/initrd.img
}
menuentry "linux-nonfb (on /dev/sdb1)" {
   insmod part_msdos
   insmod ext2
   set root='(hd1,msdos1)'
   search --no-floppy --fs-uuid --set 0f25c9d8-de98-4a8d-aa3b-5fb3eb5ef615
   linux /boot/vmlinuz BOOT_IMAGE=linux-nonfb root=UUID=0f25c9d8-de98-4a8d-aa3b-5fb3eb5ef615 resume=UUID=ba96f397-96ee-44cb-9118-eae677f3969c
   initrd (hd0,0)/boot/initrd.img
}
menuentry "failsafe (on /dev/sdb1)" {
   insmod part_msdos
   insmod ext2
   set root='(hd1,msdos1)'
   search --no-floppy --fs-uuid --set 0f25c9d8-de98-4a8d-aa3b-5fb3eb5ef615
   linux /boot/vmlinuz BOOT_IMAGE=failsafe root=UUID=0f25c9d8-de98-4a8d-aa3b-5fb3eb5ef615 failsafe
   initrd (hd0,0)/boot/initrd.img
}
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f  $prefix/custom.cfg ]; then
  source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###

[Was_Just19]

I suggest you install the PCLOS Grub to its root partition or the MBR of the external drive and make a generic 'bootloader' type entry in your main grub to call the PCLOS Grub.

Either that or make the PCLOS Grub the main controlling grub and put an entry in it to call the Mint Grub.

Either should work ......  and there should be some examples in threads in the forum.

[uncleV]

I would follow Just19s advice but if you want to boot by the Mint bootloader let's try.

Here is a stanza of your /boot/grub/grub.cfg file for PCLOS:

menuentry "linux (on /dev/sdb1)" {
   insmod part_msdos
   insmod ext2
   set root='(hd1,msdos1)'
   search --no-floppy --fs-uuid --set 0f25c9d8-de98-4a8d-aa3b-5fb3eb5ef615
   linux /boot/vmlinuz BOOT_IMAGE=linux root=UUID=0f25c9d8-de98-4a8d-aa3b-5fb3eb5ef615 resume=UUID=ba96f397-96ee-44cb-9118-eae677f3969c splash=silent vga=788
   initrd (hd0,0)/boot/initrd.img

I am some confused by this one
(hd1,msdos1)*
as I can't understand the way of addressing. Surely old-polack knows it

Anyway - as far as I know this address
(hd0,0)
doesn't make sense for GRUB2 because it starts counting from (hd0,1).

Further - as seen from your report your PCLOS is on sdb1. GRUB2 should address this as (hd1,1) (e.g. the second hard disk, the first partition of it).

I am suggesting you rename your original grub.cfg for backup, after that edit it as root and change in the three PCLOS stanzas the line
initrd (hd0,0)/boot/initrd.img
to
initrd (hd1,1)/boot/initrd.img
After that save the file with the name grub.cfg in the /boot/grub directory, reboot and see if it works. If it doesn't you can always delete it and rename the backuped file to its original name.
Please tell us what's the result.

P.S. I am curious if you installed PCLOS on that hard drive with the other hard disks detached?

------------------------
* - Well I googled this set root='(hd1,msdos1)' and it seems to be the address of the first partition of the second hard drive. So I hope we won't have address mismatch - both
set root='(hd1,msdos1)'
and the edited
initrd (hd1,1)
point to the same partition that is sdb1.

[LarryO61]

 
Thanks Uncle V! The suggestion of changing the stanzas to (hd1,1) worked. I am using PCLinuxOS to write this note. To everyone, thank you for replying and your suggestions. The PCLinuxOS community is a strong and supportive one.

[uncleV]

One note: the next time the kernel of Mint is updated you will find yourself in the same silly situation.
Yes there's a way to do your changes in Mint permanent but I forgot it.

Edit: It's good to mark the thread solved to help others find a solution.
For that purpose you should edit the title of the first post.