Surface Pro 3 hangs on grub screen after shim update if any peripherals attached

[rbrdvr]

After installing shim update (shim-signed:amd64 1.48+15.4-0ubuntu5) Surface Pro 3 running Kubuntu 21.04 (kernel 5.11.0.25-generic), hangs on boot during grub screen if _any_ peripherals attached. It could be a usb hub with nothing connected to it or an external display connected via mini displayport. System boots fine if nothing is attached.

shim-signed:amd64 1.50+15.4-0ubuntu7 (latest update afaik) didn't fix the issue

It appears Surface Pro only issue, I don't have the same problem with other computers running the same version of os with the same updates.
How do I fix it?

[oshunluvr]

Try booting different (older) kernels. Usually when I run into a hardware lock like that, a kernel change will resolve the issue. Also, be sure you have a the kernel add-ons installed - tools, hwe, modules, modules-extra, etc.

[rbrdvr]

system hangs/freezes at the beginning of grub default timeout (set to 5 seconds), on the grub screen, before kernel is loaded

so it is not a kernel problem as far as I can tell

problem started after the shim update

[jglen490]

With this occurring after a shim update, I'd be inclined to look for an efi or a UEFI setup issue.

Boot your system, but break into your UEFI setup page. Check the status of Secure boot. If it's "enabled", then disable it. Save the settings and reboot. See if that changes what happens with the offending peripherals,

[rbrdvr]

some additional observations:

1. sometimes system doesn't hang/freeze up
2. disabling secure boot doesn't affect the behavior, system may still hang before kernel is loaded with peripherals attached
it does seem to be a bit "easier" to make system lock up with secure boot enabled, but still happens with it disabled
3. sometimes system hangs before grub screen is loaded, on power up, while displaying "Surface" logo
4. adding more connected things increases probability of system freezing, for example Microsoft's Surface Dock that also provides power, or Microsoft power adapter
5. adding another peripheral during grub timeout may hang the system - this one is the one that was the easiest to replicate
6. once the grub screen is gone and kernel is loading or loaded, I can add as many peripherals as I have available and system doesn't hang

so, to sum up:

system is unstable (hangs) _only_ during grub if peripherials are attached
enabling or disabling secure boot makes no difference

once the grub is done, i can attach all the same things that hang the system during grub with no problem
none of this behavior was ever observed before the shim update


question:

is there a way to enable any debug log in grub2 and have it write to the efi partition? my root is btrfs and it doesn't look like grub2 can write to it.
or, how to I enable debug output on the screen?

[oshunluvr]

You could edit grub.cfg and add echo comments before or after each line in the boot stanza so you can see where exactly in the sequence grub is stalling. Format like this:

echo 'message here...'

Then boot without "quiet splash" and see where it stalls.

[rbrdvr]

ended up reinstalling kubuntu 21.04. It's "fixed" now. I do still have a question, see below:

interestingly, if Secure boot is enabled and I'm allowing the installer to download updates during installation, i get an error related to shim-signed:
"installed shim-signed package post-installation script subprocess returned error exit status 1" and installation fails

the only way I was able to avoid getting this error - disable secure boot, install everything, then enable secure boot. now I'm not sure if correct keys are enrolled into the uefi and that i have protection expected from secure boot.
Do I?

[jglen490]

The OS is fine. I disabled Secure Boot from the day one and never re-enabled it, nor will I.