Grub2 chainloader : Linux Mint 12 , Fedora 16 ( Linux dual boot )

Here’s an explanation of how to update the grub2 configuration.

I’ve dual-booted two Linux distributions , Linux Mint 12 and Fedora 16.

MBR (Master Boot Record ) : Linux Mint's Grub2
Linux Mint : /dev/sda6
Fedora's Grub : /dev/sda1

When upgrading the Fedora’s kernels , I need to update Linux Mint’s Grub2 configuration (MBR) so that I can boot the new Fedora’s kernel via Linux Mint’s Grub(MBR).

I’d like to change MBR :

from

Linux mint 12
Fedora 16 ( 3.1.0-7 )

to

Linux mint 12
Fedora 16 ( 3.1.0-7 )
Fedora 16 ( 3.1.6-1 ) <- boot this kernel ver. via Mint’s grub

before updating Mint’s Grub ( MBR )

Let’s check the current /boot/grub/grub.cfg on Mint.

The following lines are  for Linux mint ( Linux Mint’s Grub )

### BEGIN /etc/grub.d/10_linux ### <snip> menuentry 'Linux Mint 12 32-bit, 3.0.0-14-generic (/dev/sda6)' --class linuxmint --class gnu-linux --class gnu --class os {        recordfail        set gfxpayload=$linux_gfx_mode        insmod gzio        insmod part_msdos        insmod ext2        set root='(hd0,msdos6)'        search --no-floppy --fs-uuid --set=root b3a1ec63-246c-4711-b0ba-b14584205b71        linux   /boot/vmlinuz-3.0.0-14-generic root=UUID=b3a1ec63-246c-4711-b0ba-b14584205b71 ro   quiet splash vt.handoff=7        initrd  /boot/initrd.img-3.0.0-14-generic } <snip> ### END /etc/grub.d/10_linux ###

The followings are for Fedora 16 ( Linux Mint’s Grub )

### BEGIN /etc/grub.d/30_os-prober ### menuentry "Fedora release 16 (Verne) (on /dev/sda1)" --class gnu-linux --class gnu --class os {        insmod part_msdos        insmod btrfs        set root='(hd0,msdos1)'        search --no-floppy --fs-uuid --set=root ba2b7a10-73a2-4986-bcc5-964966fea960        linux /boot/vmlinuz-3.1.0-7.fc16.i686.PAE root=/dev/sda1        initrd /boot/initramfs-3.1.0-7.fc16.i686.PAE.img } ### END /etc/grub.d/30_os-prober ###

There are two ways :

- have MBR ( Mint’s Grub ) load Fedora’s grub ( chainloader )
- add Fedora’s new kernel parameters in MBR

way1 : have MBR ( Mint’s Grub ) load Fedora’s grub ( chainload )

on Mint , iinstall os-prober to find installed other OSes

# apt-get install os-prober -y

Fedora 16 has been installed in /dev/sda1

# os-prober /dev/sda1:Fedora release 16 (Verne):Fedora:linux

make 15_Fedora file to have MBR load Fedora’s grub

# cat /etc/grub.d/15_Fedora #!/bin/sh cat << \EOF menuentry "Fedora" {    set root='(hd0,msdos1)'  # hd0 = /dev/sda  msdos1 = sda1    chainloader +1 } EOF

# chmod u+x 15_Fedora

update grub.cfg ( MBR )

# update-grub2

The red lines are added in /boot/grub/grub.cfg

### BEGIN /etc/grub.d/15_Fedora ### menuentry "Fedora" {    set root='(hd0,msdos1)'    chainloader +1 } ### END /etc/grub.d/15_Fedora ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Fedora release 16 (Verne) (on /dev/sda1)" --class gnu-linux --class g nu --class os {        insmod part_msdos        insmod btrfs        set root='(hd0,msdos1)'        search --no-floppy --fs-uuid --set=root ba2b7a10-73a2-4986-bcc5-964966fe a960        linux /boot/vmlinuz-3.1.0-7.fc16.i686.PAE root=/dev/sda1        initrd /boot/initramfs-3.1.0-7.fc16.i686.PAE.img } menuentry "Fedora release 16 (Verne) (on /dev/sda1)" --class gnu-linux --class gnu --class os {        insmod part_msdos        insmod btrfs        set root='(hd0,msdos1)'        search --no-floppy --fs-uuid --set=root ba2b7a10-73a2-4986-bcc5-964966fea960        linux /boot/vmlinuz-3.1.6-1.fc16.i686.PAE root=/dev/sda1        initrd /boot/initramfs-3.1.6-1.fc16.i686.PAE.img } ### END /etc/grub.d/30_os-prober ###

You can boot the Fefora’s new kernel ( 3.1.6-1 ) via Mint’s grub.

way2 : add Fedora’s new kernel parameters in MBR

on Linux Mint 12

install os-prober to find installed other OSes

# apt-get install os-prober -y

Fedora 16 has been installed in /dev/sda1

# os-prober /dev/sda1:Fedora release 16 (Verne):Fedora:linux

check the file system of /dev/sda1 (Fedora16)

# grub-probe -d /dev/sda1 btrfs

mount /dev/sda1 to tmp directory to check Fedora’s grub.cfg.

# mount -t btrfs /dev/sda1 tmp

check the Fedora’s grub.cfg
Red lines are the new Fedora’s kernel 3.1.6-1.
This kernel ver. does not exist in MBR (Mint’s grub ).

### BEGIN /etc/grub.d/10_linux ### menuentry 'Fedora (3.1.6-1.fc16.i686.PAE)' --class fedora --class gnu-linux --cl ass gnu --class os {        load_video        set gfxpayload=keep        insmod gzio        insmod part_msdos        insmod btrfs        set root='(hd0,msdos1)'        search --no-floppy --fs-uuid --set=root ba2b7a10-73a2-4986-bcc5-964966fe a960        echo 'Loading Fedora (3.1.6-1.fc16.i686.PAE)'        linux   /boot/vmlinuz-3.1.6-1.fc16.i686.PAE root=UUID=ba2b7a10-73a2-4986 -bcc5-964966fea960 ro rd.md=0 rd.lvm=0 rd.dm=0 quiet rhgb rd.luks=0 LANG=ja_JP.U TF-8  KEYTABLE=jp106        echo 'Loading initial ramdisk ...'        initrd /boot/initramfs-3.1.6-1.fc16.i686.PAE.img } menuentry 'Fedora Linux, with Linux 3.1.0-7.fc16.i686.PAE' --class fedora --clas s gnu-linux --class gnu --class os {        load_video        set gfxpayload=keep        insmod gzio        insmod part_msdos        insmod btrfs        set root='(hd0,msdos1)'        search --no-floppy --fs-uuid --set=root ba2b7a10-73a2-4986-bcc5-964966fea960        echo    'Loading Linux 3.1.0-7.fc16.i686.PAE ...'        linux   /boot/vmlinuz-3.1.0-7.fc16.i686.PAE root=UUID=ba2b7a10-73a2-4986-bcc5-964966fea960 ro rd.md=0 rd.lvm=0 rd.dm=0 quiet rhgb rd.luks=0 LANG=ja_JP.UTF-8  KEYTABLE=jp106        echo    'Loading initial ramdisk ...'        initrd  /boot/initramfs-3.1.0-7.fc16.i686.PAE.img }

on Mint , make 15_Fedora file and add the above red lines

# cat /etc/grub.d/15_Fedora #!/bin/sh cat << \EOF menuentry 'Fedora (3.1.6-1.fc16.i686.PAE)' --class fedora --class gnu-linux --cl ass gnu --class os {        load_video        set gfxpayload=keep        insmod gzio        insmod part_msdos        insmod btrfs        set root='(hd0,msdos1)'        search --no-floppy --fs-uuid --set=root ba2b7a10-73a2-4986-bcc5-964966fe a960        echo 'Loading Fedora (3.1.6-1.fc16.i686.PAE)'        linux   /boot/vmlinuz-3.1.6-1.fc16.i686.PAE root=UUID=ba2b7a10-73a2-4986 -bcc5-964966fea960 ro rd.md=0 rd.lvm=0 rd.dm=0 quiet rhgb rd.luks=0 LANG=ja_JP.U TF-8  KEYTABLE=jp106        echo 'Loading initial ramdisk ...'        initrd /boot/initramfs-3.1.6-1.fc16.i686.PAE.img } EOF

# chmod u+x 15_Fedora

update grub.cfg

# update-grub2 Generating grub.cfg ... Found linux image: /boot/vmlinuz-3.0.0-14-generic Found initrd image: /boot/initrd.img-3.0.0-14-generic Found linux image: /boot/vmlinuz-3.0.0-13-generic Found initrd image: /boot/initrd.img-3.0.0-13-generic Found linux image: /boot/vmlinuz-3.0.0-12-generic Found initrd image: /boot/initrd.img-3.0.0-12-generic Found memtest86+ image: /boot/memtest86+.bin Found Fedora release 16 (Verne) on /dev/sda1 done

Fefora’s new kernel has been added in MBR’s grub.cfg ( Mint )

### BEGIN /etc/grub.d/15_Fedora ### menuentry 'Fedora (3.1.6-1.fc16.i686.PAE)' --class fedora --class gnu-linux --cl ass gnu --class os {        load_video        set gfxpayload=keep        insmod gzio        insmod part_msdos        insmod btrfs        set root='(hd0,msdos1)'        search --no-floppy --fs-uuid --set=root ba2b7a10-73a2-4986-bcc5-964966fe a960        echo 'Loading Fedora (3.1.6-1.fc16.i686.PAE)'        linux   /boot/vmlinuz-3.1.6-1.fc16.i686.PAE root=UUID=ba2b7a10-73a2-4986 -bcc5-964966fea960 ro rd.md=0 rd.lvm=0 rd.dm=0 quiet rhgb rd.luks=0 LANG=ja_JP.U TF-8  KEYTABLE=jp106        echo 'Loading initial ramdisk ...'        initrd /boot/initramfs-3.1.6-1.fc16.i686.PAE.img } ### END /etc/grub.d/15_Fedora ###

You can boot the Fedora’s new kernel (3.1.6-1) via Mint’s grub ( MBR )

You need to issue update-grub2 command in both the way1 and the way2 after upgrading Fedora’s kernel.
In case of way1 , all you have to do is just issuing update-grub2.
However , in case of way2 , you need to edit  /etc/grub.d/15_Fedora and issue update-grub2.
So I think the way1 would be a better operation than the way2.