[SOLVED] grub-install command failing for UEFI

Question

I downloaded the 8/2013 iso and burned it with dd. I have an ASUS Rampage IV Extreme motherboard. I was booted into efi mode on both the ISO and in the chroot (the /sys/firmware/efi directory did exist).
I followed the instructions in the Beginner's Guide, but with a 512 MB EFI partition as sda1, 50 GB root as sda2, the rest of my 256 GB SSD as /home, and a 100 GB space on my HDD as /tmp. Everything was ext4 and the EFI partition was a fat32. The EFI partition was mounted on /boot of the new install, as the beginner's guide stated it should be
Everything worked until I get to the part of installing GRUB. Before installing, I again confirmed that /sys/firmware/efi existed. When booting, on the motherboard boot selection screen, it showed 2 options for my USB, one with the name of my drive and another with [UEFI] in front of the drive name. I selected the UEFI option, so I was booted into UEFI mode, and the USB's bootloader also gave options to boot into a UEFI shell instead of the standard Arch ISO bootloader I get on MBR computers (though I did not try those EFI shell options). I looked into te /sys/firmware/efi/efivars directory and it had 2 items in it
Going back to the chroot's / directory, I did the first command in the guide for installing grub (after installing grub and efibootmgr with pacman).
umount /sys/firmware/efi/efivarsk
This gave the error that the directory was not mounted
modprobe -r efivars and modprobe efivars worked correctly (or at least they didn't output any errors).
When I got to
grub-install --efi-directory=/boot --bootloader-id=arch_grub --recheck
it gave this error:
Fatal: Couldn't open either sysfs or procfs directories for accessing EFI variables.
I searched around on the interwebs and for every other person this problem was occuring because they were booted into BIOS mode instead of UEFI mode, and booting the USB into UEFI mode fixed the problem for them. However, the /sys/firmware/efi directory exists and I made sure to boot into EFI mode in the BIOS.
Are there any other reasons that this could be happening?
Also, is there really any advantage to GPT/EFI booting over GPT/BIOS booting other than a 1-2 second shorter boot time?
Last edited by subraizada3 (2013-08-23 21:10:37)

Answer 1

You burnt it to CD?DVD, right? Not dd? Because that won't create an EFI bootable USB key, for example.
modprobe efivars never gives errors (that I've seen). The question is whether the directories are populated. It isn't enough for /sys/firmware/efi to exist. /sys/firmware/efi/vars/ should be full of a *lot* of stuff. In fact /sys/firmware/efi/efivars/ should have lots of stuff before you umount it.
Did you modprobe before arch-chroot? That's essential if the installed kernel is different from the one on the installer (which is very likely).
I think you are confused. There's no such thing as GPT/MBR booting.
GPT and MBR are 2 ways of partitioning disks. GPT has various advantages explained on the wiki page.
EFI and BIOS are 2 ways of booting.
In my personal opinion, if BIOS booting works for you, I'd stick with BIOS. EFI is buggy - why be a guinea pig if you can help it?
Also in my personal opinion, if you can only use GPT in EFI mode, it is worth the hassle to use EFI to reap the benefits of GPT.
At least, those are the decisions I made. Nothing will convince my laptop to boot BIOS mode with a GPT disk. MBR+BIOS is fine but GPT+BIOS is a non-starter. So I use GPT+EFI.  On machines that don't care, I prefer BIOS+GPT.
If you are dual booting Windows, I believe BIOS+GPT may not be an option but I'm not certain of this.
Your kilometres may vary.
By the way, you almost certainly do not want a partition for /tmp unless you are extraordinarily short of RAM and even then...