dev's major/minor not captured in /sys/power/resume

[monochromec]

When trying to configure hibernation on Noble Numbat, systemd-sleep hibernate complains about
"Failed to find location to hibernate to: Invalid argument" caused by a "0:0" entry in /sys/power/resume

Current configuration:

1) Legacy boot configuration (non-UEFI!)

2) Dual swap space configuration (/etc/fstab excerpt for swap partition and file):
UUID=c323a060-1b69-48af-a5bb-395f5d05fb60 none swap sw 0 0
/swap none swap sw,pri=2 0 0

(swap file is the primary and only option for hibernation as partition is too small)

2) resume config in /etc/initramfs-tools/conf.d/resume with the correct UUID and offset:

RESUME=UUID=7799882e-189c-484b-b9d4-f9e302859b0b resume_offset=39608320

(blkid: /dev/sda1: UUID="7799882e-189c-484b-b9d4-f9e302859b0b" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="4f6b947f-01")

3) Correct grub config:

GRUB_CMDLINE_LINUX="resume=UUID=7799882e-189c-484b-b9d4-f9e302859b0b resume_offset=39608320 acpi_enforce_resources=lax"

Suspect a regression issue with systemd-255 as the issue did *not* appear with Focal Fossal (system-245) and only surfaced after the upgrade to 24.04.

Work-around:

Amend /etc/rc.local (if this is enabled via systemd) with:

"lsblk | fgrep $(basename $(df -P $(fgrep swap /etc/fstab | grep '^/' | cut -d' ' -f1) | grep '^/' | cut -d' ' -f1)) | cut -d' ' -f4 >/sys/power/resume"

Please let me know if more info is required - more than happy to help!

[monochromec (monochromec)]

Please note that the work-around only works with one swap file. Alternatively simply hardcode the device in the above statement.