[bug #60995] Surface Pro 3 hangs on grub if peripherals attached

[konst]

URL:
  <https://savannah.gnu.org/bugs/?60995>

                 Summary: Surface Pro 3 hangs on grub if peripherals attached
                 Project: GNU GRUB
            Submitted by: rbrdvr
            Submitted on: Sat 31 Jul 2021 08:38:42 PM UTC
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: Hardware-specific
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 
                 Release: other
         Discussion Lock: Any
         Reproducibility: Intermittent
         Planned Release: None

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Details:

grub 2.04-1ubuntu45
shim-signed 1.50+15.4-0ubuntu7

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

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






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