UC20 boot error "Failed to make path absolute" on Fitlet2 device

[snapcore]

UC20 boot error "Failed to make path absolute" on Fitlet2 device

[anonymouse64]

No, we just need time to test out adding those kernel modules to the initrd and then test that it fixes the issue. Unfortunately testing changes like these is rather involved since you need to add the snakeoil keys to a device's platform trusted keys, which is easy to do in QEMU, but then requires setting up QEMU to boot from a virtual USB drive which I have not yet had time to play around with very much.

[anonymouse64]

What channel are you using for the kernel snap? Have you tried using the edge channel of the kernel snap?

Hi, can you boot into a live 20.04 session and follow these instructions for determining what kernel module the disk drive/device that you are trying to use as the install device for UC20 needs?

https://unix.stackexchange.com/questions/97676/how-to-find-the-driver-module-associated-with-a-device-on-linux/125272#125272

I suspect that this is similar to https://bugs.launchpad.net/ubuntu-core-initramfs/+bug/1896528 but probably a different kernel module since the ones mentioned in that bug have been added.

[osteenbergen]

I'm usung 20/stable which is revision 743.

Seems to be the only version available in all channels.

  20/stable:        5.4.0-70.78.1  2021-03-24 (743) 284MB -
  20/candidate:     5.4.0-70.78.1  2021-03-24 (743) 284MB -
  20/beta:          5.4.0-70.78.1  2021-03-24 (743) 284MB -
  20/edge:          5.4.0-70.78.1  2021-03-24 (743) 284MB -

Using the latest Ubuntu 20.04 live CD image (kernel 5.8.0-43-generic) it reports:

$ ls -l /dev/sdb
brw-rw---- 1 root disk 8, 16 Mar 26 14:58 /dev/sdb
$ readlink /sys/dev/block8\:16/device/driver
../../../../../../../../../bus/scsi/drivers/sd

The script posted returns the following drivers: sd, usb-storage, usb, xhci_hcd.
There is a disk installed in the system which also uses the sd driver and as parent the ahci driver
Tried booting from a SD card (device has a microSD reader) which uses mmcblk and sdhci-pci drivers, but that resulted in the same error.

[osteenbergen]

Using the Ubuntu Live CD and flashing the image to the internal disk works.

[anonymouse64]

@osteenbergen to be clear, you ran the mentioned script against the USB device (or SD card) you are trying to boot from, not the media that the Ubuntu Live CD was running from?

[osteenbergen]

Yes I did ran them against the /dev/sdc (a internal, b was live cd) and /dev/mmcblk0. Now that UC20 boots I also ran the script from within UC20 and it returns the same information for the USB key.

[osteenbergen]

Hi, do you need more details/tests to be run before this can be solved? Thanks

[stulluk]

IMHO, this issue could be related to snapcore/snapd#10861 .

Let us see if that fixes this issue as well.

[xanonid]

@stulluk With recent snapd (2.53.1+git284.g482f8c7), I can reproduce the issue on booting to ubuntu core 20 (using a usb key on a fast pc). Seems that the PR did not fix it.

[anonymouse64]

@xanonid unfortunately there is quite a lag between landing fixes to snap-bootstrap in snapd and being able to test that change in the core-initrd, since that change needs to land in the deb of snapd in the snappy-dev/image PPA, and then the ubuntu-core-initramfs debian package in the snappy-dev/image PPA needs to be rebuilt, then the kernel snaps need to be rebuilt to pick up that new version of the debian package.

Perhaps @alfonsosanchezbeato or @stulluk could trigger a rebuild/version bump of the ubuntu-core-initramfs debian package in that PPA, then the next kernel snap rebuild will get the snap-bootstrap from 2.53.1.