Hi Vagrant,
Vagrant Cascadian <vagr...@debian.org> writes:
> On 2021-05-02, Vagrant Cascadian wrote:
>> Unfortunately, guix doesn't currently support booting off of a separate
>> /boot partition, since the kernel and initrd are in /gnu/store; your
>> bootloader needs to be able to mount the partition that /gnu/store is
>> located on.
>>
>> The workaround would be to manually copy all files mentioned in grub.cfg
>> (kernel, initrd, possibly others) into a partition somewhere on boot
>> media, and tweak the grub.cfg appropriately...
>>
>>
>> There are several cases where this sort of thing would be desireable:
>>
>> * The above scenario; the system does not expose an NVMe drive from EFI
>> or BIOS.
>>
>> * Using u-boot and you want root on lvm, raid, encryption, etc. which
>> u-boot does not support
>
> * Using luks1 format for /boot and luks2 format for / (unless grub2
> learns how to read luks2 already/soon)
On top of the above use cases, I'll add one I found recently, after
upgrading my disk array to 2.5 TiB on my aging BIOS desktop:
* Keep boot files under the maximum 2 TiB addressable sector on BIOS
(non-UEFI) systems using > 2 TiB drives.
The problem would manifest itself by this cryptic GRUB error:
"error: attempt to read or write outside of disk `proc'"
The solution was to have a separate *and* standalone boot partition.
The separate part is easy; just create a new partition and mount it as
/boot in your config file system definitions.
The second "standalone" part is not taken care by Guix System yet; with
the help of Tobias I devised the following script that copies the
minimum (init RAM disks and kernel images) to /boot and strips the
prefixes on these paths, if any (I use Btrfs subvolumes):
--8<---------------cut here---------------start------------->8---
#!/usr/bin/env bash
set -e
# Copy kernel and initrd images to /boot
images=$(grep -E '^ (linux|initrd) ' /boot/grub/grub.cfg \
| awk '{ print $2 }' | sed 's|.*/gnu|/gnu|g' | sort | uniq)
for image in $images; do
mkdir -p /boot$(dirname $image)
if [ ! -e /boot$image ] || ! cmp -s $image /boot$image; then
echo copying cp $image to /boot$image... > /dev/error
cp $image /boot$image
fi
done
# Adjust /boot/grub/grub.cfg.
sed -E -e 's/.*search.*--set.*//' \
-e 's/^insmod luks.*//' \
-e 's/^cryptomount.*//' \
-e 's,^( (linux|initrd) )[^ ]*(/gnu/[^ ]* ?),\1\3,' \
-i.bak /boot/grub/grub.cfg
--8<---------------cut here---------------end--------------->8---
It's on my TODO to address this properly in Guix when I'll have the
bandwidth.
I hope that helps,
Thanks!
Maxim
