[CentOS] Location of grub.conf etc. with UEFI boot (CentOS 6)

Wed Oct 11 12:46:16 UTC 2017
Jonathan Billings <billings at negate.org>

On Oct 11, 2017, at 8:38 AM, Toralf Lund <toralf.lund at pgs.com> wrote:
> What's the proper/normal way of setting up GRUB for a CentOS 6 installation that boots using UEFI? I've recently set up such a system, but for technical reasons I mentioned in an earlier post, I booted in "legacy" mode during installation, which meant I didn't get the correct UEFI boot configuration, and had to set it up subsequently "by hand". I've managed to get the system to start up, but I had to place grub.conf under "/EFI/redhat/" on the EFI partition; without it, the system only boots into the grub shell. Is this normal, or is GRUB supposed to be able to find grub.conf under /boot? If not, how are updates on kernel upgrade etc. supposed to get done? Do I need a symlink from /boot/grub/grub.conf to the EFI parition? And will grub-install help with some of this? I haven't dared to try it, as I'm afraid it may break everything because it assumes an "MBR" configuration, or something.
> Also, how is /boot supposed to be set up anyway? Will it still normally be configured as a separate partition?
> Yeah, I know, I could re-install in UEFI mode (as I think I know how now), but I'm hoping you will save me from the effort. I also have a workable system anyhow, but kernel upgrades could be an issue, and it's nice to know the "right" way of setting up.

Yes, UEFI boots with a UEFI grub executable, and it looks for a grub.cfg in the /EFI/redhat/ directory, next to the grub executable. 

Typically, you have the UEFI partition mounted as /boot/efi, and grub knows to find the grub.cfg in the subdirectory there.  The kernel package runs ‘grubby’ which knows how to update grub if there’s an EFI partition mounted. 

My experiences have been only with CentOS7 and RHEL7 with UEFI, which uses grub2. However, the RHEL6 documentation confirms these paths: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/s2-grub-whatis-booting-uefi.html

Jonathan Billings <billings at negate.org>