CentOS - Oct 2017 - Location of grub.conf etc. with UEFI boot (CentOS 6)

Hi,

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.

Thanks,


 ?-Toralf

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>