EFI and /boot [solved]

dtw · 2015-10-22 09:01:35

Just a sense check really. I'm using (U)EFI, syslinux and GPT disks.

I currently mount my ESP to /boot, so it contains all my kernels and UEFI loaders/applications. However, I want to install an alternate distribution and I know I don't want to share /boot between Arch and the new install.

Would it make sense to move /boot (ie. my Arch kernels) back to my Arch install /root, then mount what's left of the ESP files to /boot/EFI?

Then I can do the same on the other distro and share the ESP without conflicting /boot folders? Makes sense, right? Or have I missed something?

Last edited by dtw (2015-10-22 13:39:40)

olive · 2015-10-22 09:12:34

Syslinux has very limited capability in UEFI mode. You can install refind in the EFI partition and configure it to go and fetch your kernel in the archlinux partition (it has driver for ext{2,3,4} and other filesystems). Grub is another possibility but it can be more difficult to configure.

What you do with Archlinux is feasible in the same way with other distributions. Many of them configure your system automatically at install time and it is not always easy to really know what they are doing. A workaround is to install them the way they want and reconfigure the boot loader afterwards. If the other distribution use grub, you can just launch its grub.efi (not sure of the exact name) from refind (or launch the appropriate kernel directly with the appropriate parameters). For your information, I show you an example of refind configuration:

timeout 5
scanfor manual
textonly true
textmode 1024
showtools shell, memtest, gdisk, apple_recovery, mok_tool, shutdown, reboot, firmware
default_selection ArchLinux

menuentry "ArchLinux" {
volume 71bd290b-d32a-4463-b4d7-99ee7c761af4
loader /boot/vmlinuz-linux
options "root=UUID=b61e88c7-153f-456b-9aac-421fc128b08a ipv6.disable=1 rw initrd=/boot/intel-ucode.img initrd=/boot/initramfs-linux.img"

submenuentry "Force fsck" {
add_options "fsck.mode=force"
}

submenuentry "Text mode" {
add_options "systemd.unit=multi-user.target nomodeset"
}
}

menuentry "System Rescue CD" {
volume 71bd290b-d32a-4463-b4d7-99ee7c761af4
loader /boot/sysrcd/isolinux/rescue64
options "subdir=/boot/sysrcd setkmap=be docache video=HDMI-A-1:d radeon.audio=0 initrd=/boot/sysrcd/isolinux/initram.igz"
}

menuentry "Windows 7" {
loader /efi/Microsoft/Boot/bootmgfw.efi
}

Last edited by olive (2015-10-22 09:13:56)

dtw · 2015-10-22 09:24:52

Thanks, Olive I *just* read this on the Wiki:

Syslinux is (currently) limited to loading only files from the partition where it was installed

So, yup, I can't do exactly what I described!

I think I might do what you have suggested and let the new distro set it's bootloader up and then reconfigure that to boot my Arch Linux install.

I could install rEFInd alongside syslinux, right? I might migrate to rEFInd anyway.

olive · 2015-10-22 09:30:15

You can install refind alongside syslinux. But what's the point? If you have refind correctly installed, use it to launch the kernel directly; it would be unnecessary complication to launch syslinux that would itself launch the kernel. Note that some other distributions might be able to auto detect arch and add an entry for it. The problem with these automatic tools is that if they don't work it's usually difficult to correct the problem.

Last edited by olive (2015-10-22 09:36:16)

Scimmia · 2015-10-22 12:59:51

Can I ask why you don't want to share /boot?

dtw · 2015-10-22 13:26:00

Scimmia wrote:

Can I ask why you don't want to share /boot?

I understood it was bad practice as you can easily accidently overwrite files owned by the other distro.

Last edited by dtw (2015-10-22 13:28:12)

dtw · 2015-10-22 13:27:50

olive wrote:

You can install refind alongside syslinux. But what's the point? If you have refind correctly installed, use it to launch the kernel directly; it would be unnecessary complication to launch syslinux that would itself launch the kernel. Note that some other distributions might be able to auto detect arch and add an entry for it. The problem with these automatic tools is that if they don't work it's usually difficult to correct the problem.

As it turns out, my butterfingers solved this problem for me when I `rm -r`ed the whole of /boot and spent about 3 hours trying to restore my system to a bootable state. Syslinux has now gone the way of the dinosaur.

Epic skillz.

Scimmia · 2015-10-22 13:34:09

dtw wrote:

Scimmia wrote:
Can I ask why you don't want to share /boot?
I understood it was bad practice as you can easily accidently overwrite files owned by the other distro.

That should not be a problem unless your installing variants of the same distro (Arch and Manjaro, for example).

Last edited by Scimmia (2015-10-22 13:36:21)

dtw · 2015-10-22 13:39:25

Scimmia wrote:

That should not be a problem unless your installing variants of the same distro (Arch and Manjaro, for example).

As olive said, you never know what some installers are going to do and you might set some mount points and *pop* the damage is done. Better just to avoid the possibility.

Probably could have got away with it but instead I gave myself a tonne of hassle avoiding it!

Arch Linux

#1 2015-10-22 09:01:35

EFI and /boot [solved]

#2 2015-10-22 09:12:34

Re: EFI and /boot [solved]

#3 2015-10-22 09:24:52

Re: EFI and /boot [solved]

#4 2015-10-22 09:30:15

Re: EFI and /boot [solved]

#5 2015-10-22 12:59:51

Re: EFI and /boot [solved]

#6 2015-10-22 13:26:00

Re: EFI and /boot [solved]

#7 2015-10-22 13:27:50

Re: EFI and /boot [solved]

#8 2015-10-22 13:34:09

Re: EFI and /boot [solved]

#9 2015-10-22 13:39:25

Re: EFI and /boot [solved]

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