I'm using Grub2 because it support some nice ways to theme it.
The setup of it is slightly confusing though and I never got around with the auto configuration stuff of it.
I'm going to explain in this post how you can set it up with your own config files which is also a little bit more gentooish.
The Installation:
Grub2 is still masked by keyword **, it needs to be unmasked.
First we need the /etc/portage folder:
mkdir -p /etc/portage
Then we need to decide which version we want, the latest release snapshot or the live gits.
For gits:
echo "sys-boot/grub **" > /etc/portage/package.keywords
For the latest release snapshot:
echo "=sys-boot/grub-2* **" > /etc/portage/package.keywords
I'm using gits without any troubles.
Now we are able to emerge it.
emerge grub:2
The Configuration:
We need to disable all autoconfig scripts in /etc/grub.d.
cd /etc/grub.d
chmod -x 10_linux
chmod -x 20_linux_xen
chmod -x 30_os-prober
Now the custom configuration for our dualboot system.
Open 40_custom with nano:
nano 40_custom
Linux Part:
menuentry 'Navi 3.0.26' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
linux (hd0,msdos5)/vmlinuz-3.0.26-tuxonice rootfstype=btrfs root=/dev/sda7 ro rootflags=subvol=root quiet
}
menuentry:
It's the name which should be displayed in grub2, choose whichever you want.
set gfxplayload:
A built in framebuffer. Set it either to keep or auto.
insmod gzio:
Loads the gzip module to unpack the kernel image.
insmod part_msdos:
Load the msdos partition table module.
linux:
Loads the kernel with several parameters.
Let's have a look at it step by step:
(hd0,msdos5):
That's your boot partition where your kernel is located. Grub2 starts to count hdds at 0 and partitions at 1. So (hd0,msdos5) is the first hdd and the fifth msdos partition.
vmlinuz-3.0.26-tuxonice:
That's the kernel which should be loaded when you choose to boot this menu entry. So (hd0,msdos5)/vmlinuz-3.0.26-tuxonice boots the kernel vmlinuz-3.0.26-tuxonice from the first hdd and fifth partition.
rootfstype:
The choosen filesystem for root. It has to match the actual filesystem of your root partition. It's set to btrfs in my case.
root:
This option has to be set to the hdd and partition where your root is located. My grub2 loads /dev/sda7 as root.
ro:
Mount the root readonly during boot time. It will be later remounted with rw flags through fstab.
rootflags:
This is only needed for btrfs. It indicates which subvolume contains the root. Set it to the name of your root subvolume which you've created in your btrfs pool.
quiet:
Prevents spamming tons of debug output during boot time. Unset this option if your system doesn't boot and you'll see some nice error messages.
Windows Part:
menuentry 'The Devils Instrument' {
insmod part_msdos
insmod chain
chainloader (hd0,msdos2)+1
}
menuentry:
Again the name which should be displayed.
indmod part_msdos:
And the partition table type.
insmod chain:
Since Windows comes with an own bootloader on the second partition, we need to chainload it and need the chain module.
chainloader:
The actual chainloader. It loads the Windows bootloader from (hd0,msdos2), the first hdd and second partition.
The addon +1 indicates on which partition Windows is installed. It's on the third partition in my case, so I need to count up one partition.
If the Windows bootloader would be on the second partition but Windows itself on the fifth, then it would look like this: chainloader (hd0,msdos2)+3
This was all we need for now, we will later alter it a little bit for splash support and fancy things but that will be covered in a later chapter.
Hit ctrl+o to save the config, then ctrl+x to leave the editor.
Create config and write Grub2 into mbr:
Now we're going to create the config. Make sure that /boot is mounted and /etc/grub.d/40_custom executeable.
mkdir -p /boot/grub2
chmod +x /etc/grub.d/40_custom
grub2-mkconfig -o /boot/grub2/grub.cfg
It might show some warnings about /sys not loaded or not readable, but you can ignore them.
Check the created config file in /boot/grub2. It sometimes happens that it isn't created at all.
It should look like this, it's only important for now, that the custom part is added to it:
navi lia # cat /boot/grub2/grub.cfg
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub2-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#
### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
load_env
fi
set default="0"
if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi
export menuentry_id_option
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 load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}
if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_msdos
insmod btrfs
set root='hd0,msdos7'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos7 --hint-efi=hd0,msdos7 --hint-baremetal=ahci0,msdos7 79ae43bc-38b5-494b-9f07-0f3190096236
else
search --no-floppy --fs-uuid --set=root 79ae43bc-38b5-494b-9f07-0f3190096236
fi
font="/root/usr/share/grub/unicode.pf2"
fi
if loadfont $font ; then
set gfxmode=1366x768
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=
insmod gettext
fi
terminal_input gfxterm
terminal_output gfxterm
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 b1008699-03ad-4d72-8213-ec028739292a
else
search --no-floppy --fs-uuid --set=root b1008699-03ad-4d72-8213-ec028739292a
fi
insmod gfxmenu
loadfont ($root)/grub2/themes/remix/bauhaus.pf2
loadfont ($root)/grub2/themes/remix/dejavu.pf2
insmod png
set theme=($root)/grub2/themes/remix/theme.txt
export theme
if sleep --interruptible 0 ; then
set timeout=10
fi
### END /etc/grub.d/00_header ###
### 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.
### BEGIN navi main ###
menuentry 'Navi 3.0.26' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
linux (hd0,msdos5)/vmlinuz-3.0.26-tuxonicenavi rootfstype=btrfs root=UUID=79ae43bc-38b5-494b-9f07-0f3190096236 ro rootflags=subvol=root quiet splash
initrd /initramfs-3.0.26-tuxonicenavi.img
}
menuentry 'The Devils Instrument' {
insmod part_msdos
insmod chain
chainloader (hd0,msdos2)+1
}
### END /etc/grub.d/40_custom ###
And the final step, the install:
grub2-install --no-floppy /dev/sda
We are almost ready to reboot, just some minor steps are ahead of us: Internet configuration, fstab and root password.
