If you have a machine with UEFI, then I have good news for you:
- the firmware is able to read GPT partition table (by the way, it's the best partition table format at all)
- it's able to read data from FAT32 filesystem from you system partition (GPT uses partition type specific UUIDs to identify partitions)
- it's possible to use more then one boot loader (it means that you can try another boot loader and your original boot method won't be affected)
- you can modify your UEFI boot setting from Linux command line (reboot -> bios -> reboot is unnecessary)
- all your configured boot loaders are visible in your bios boot menu (e.g. F12 for ThinkPad)
Install gnu-efi library and EFI boot manager (for example for Fedora):
# yum install gnu-efi efibootmgrcompile gummiboot:
$ git clone git://anongit.freedesktop.org/gummiboot $ cd gummiboot $ makecheck your partition table, /dev/sda1 is usually the system partition (from EFI point of view), use partx(8) to see more details:
# partx -n 1 /dev/sda NR START END SECTORS SIZE NAME UUID 1 2048 2050047 2048000 1000M EFI System Partition 623b2882-c50b-48af-b3f8-f19e8639b02bthe partition with FAT filesystem is mounted on /boot/efi, use findmnt(8) to see more details:
# findmnt /dev/sda1 TARGET SOURCE FSTYPE OPTIONS /boot/efi /dev/sda1 vfat rw,relatimeif you have UEFI machine than the partition is probably already initialized by your distribution.
Now install the boot loader:
# mkdir -p /boot/efi/EFI/gummiboot # cp gummiboot.efi /boot/efi/EFI/gummiboot/inform your UEFI about the new boot loader:
# efibootmgr -c -L "Gummiboot" -l '\EFI\gummiboot\gummiboot.efi'now in your bios boot menu will be a new entry "Gummiboot". Note that UEFI uses windows-like paths, so '\' is correct. The efibootmgr(8) is a command line util to manipulate with boot EFI variables, you need kernel with /sys/firmware/efi/vars support (for example standard Fedora kernel).
# efibootmgr -vto see more details, you can also change boot order and another things by efibootmgr.
The last step is to add entry (kernel) to gummiboot, there is a nice script in gummiboot in repository:
loader-postinst.sh kernel-version path-to-kernelyou can run this script manually or you can add the script into /etc/kernel/postinst.d (this directory does not exist by default on Fedora, mkdir -p is your friend...), then the script will be automatically executed after new kernel install.
The script copies the kernel to /boot/efi/
The script also creates /boot/efi/loader/entries/*.conf file with kernel command line from /etc/kernel/cmdline, paths to kernel, initrd. etc.
we have kernel in boot loader independent directory, you can use another boot loader (UEFI Shell, elilo, etc.) to read the kernel images all is accessible for UEFI firmware on FAT filesystem (boot loader does not have to support ext4 filesystem for example) separate config files for each kernel in /boot/efi/loader/entries/ directory /etc/kernel/postinst.d based solution is extendable and open for alternative boot loaders.