On 2026-02-10, [email protected] wrote: > Greetings, > > I've just finished installing a new system, choosing systemd-boot > rather than grub. The handbook says that /etc/kernel/cmdline should > contain 'quiet splash', but that's clearly not the whole story so I > improvised. > > 'blkid | grep nvme0n1p5' shows this: > > /dev/nvme0n1p5: LABEL="RootFS" > UUID="7ab169d9-03cb-44ce-98f6-1955c2458a4c" BLOCK_SIZE="4096" > TYPE="ext4" PARTLABEL="root" > PARTUUID="aeb1b1eb-7995-44ac-84ad-0e999ff4459d" > > ...so I put this into /etc/kernel/cmdline: > > root=UUID=7ab169d9-03cb-44ce-98f6-1955c2458a4c quiet splash > > Then on rebooting, I get 'Cannot open blockdev' or similar. > > Should there be some punctuation in my command line? Or perhaps I > should have specified the PARTUUID instead of the device UUID. This is > one of the few places where the handbook doesn't show an example. > > I can't check online at the moment because the site's down.
I thought this was documented in a text file under Documentation/, but currently this is what I've found: admin-guide/kernel-parameters.txt refers (under "boot=") to «the early_lookup_bdev comment in block/early-lookup.c for details.» This, in turn lists several possibilities, but *not* UUID, just PARTUUID: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/block/early-lookup.c#n217 (Same link but with the id of the current commit, in order to have a stable line number:) https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/block/early-lookup.c?id=b8c873edbf35570b93edfeddad9e85da54defa52#n217 Or, locally: /usr/src/linux/Documentation/admin-guide/kernel-parameters.txt , and /usr/src/linux/block/early-lookup.c Now this is about linux, the kernel, I've no idea whether systemd-boot allows something more. -- Nuno Silva
