I also lack the experience with guile but it sounds very sensible to
me. I can confirm that just fixing the grub-menu entries with the
subvol path works. I have been invoking guix system reconfigure with a
bash script that in the end calls a grubfix function below with the
path to each newly generated grub.cfg:
In my case the subvol is located at /snap2_rw
function grubfix(){
sudo sed -i "s/linux\ \/gnu/linux\ \/snap2_rw\/gnu/g" "$1"
sudo sed -i "s/initrd\ \/gnu/initrd\ \/snap2_rw\/gnu/g" "$1"
sudo sed -i "s/--set\ \/gnu/--set\ \/snap2_rw\/gnu/g" "$1"
}
Your suggestion to do this directly in config.scm sounds great.
Best regads,
David L
On Sun, 27 Jan 2019, Svante v. Erichsen wrote:
The subvolume and the mount point are independent issues.
For example, I have a subvolume named @ as root volume:
(file-system
(device "/dev/mapper/hd")
(mount-point "/")
(type "btrfs")
(options "compress=lzo,ssd,subvol=@"))
It also appears that the subvolume name must be prepended to the path as if it
just was an ordinary directory (grub.cfg):
…
linux /@/gnu/store/…
…
I could not yet confirm this from documentation, but it works like that for me.
(I semi-manually edit the generated grub.cfg currently.)
So, additionally to stripping the mount point, the subvolume needs to be
prepended (grub.scm):
(let ((kernel (prepend-subvol device-subvol
(strip-mount-point device-mount-point
kernel)))
(initrd (prepend-subvol device-subvol
(strip-mount-point device-mount-point
initrd))))
…)
This would mean that the menu-entry structure needs the subvol information.
However, I wouldn't want to parse this from the options field in the file-system
entry, so I'd propose allowing a list there, maybe like this:
(file-system
(device "/dev/mapper/hd")
(mount-point "/")
(type "btrfs")
(options '(("compress" . "lzo")
"ssd"
("subvol" . "@"))))
On the other hand, it might be surprising that declaring the options like this
would work for subvols, while using a string doesn't, especially when some older
documentation/blogs/gists is still hanging around on the internet, so maybe it
would be necessary to parse the options anyway (to this list structure).
I'm lacking experience in guix and guile, so making this work and submit a patch
will take me some time.
Do you think this is sensible?
--
Svante von Erichsen
GPG fingerprint: A78A D4FB 762F A922 A495 57E8 2649 9081 6E61 20DE
