[Bug 93281] Kernel modesetting causes the kernel to lock up during boot on a late 2011 MacBook Pro

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=93281

--- Comment #13 from Roland Scheidegger <rscheidegger at gmx.ch> ---
(In reply to Alex Jordan from comment #12)
> (In reply to Roland Scheidegger from comment #11)
> > 3) via grub-efi (looks like this is what you do?).
> 
> Yeah, this is what I do. Apple EFI loads, loads GRUB by default (can't
> remember the exact magic incantation of Apple `bless` I used to make this
> work), and then GRUB loads the Linux kernel.
> 
> $ apt show grub2 | grep Version
> Version: 2.02~beta2-21
> 

It is quite possible this was never actually fixed (you should get some "radeon
0000:01:00.0: Invalid ROM contents" and "[drm:radeon_get_bios] *ERROR* Unable
to locate a BIOS ROM" if it doesn't work due to this).
There's plenty of bugs filed all around (here's another one:
https://bugzilla.redhat.com/show_bug.cgi?id=765954) with various obscure
workarounds all boiling down to pretty much the same (I never tried those
suggesting disabling kms, as I wouldn't describe a ums setup as "working" in
any case even if you can get some display output) and I haven't seen anyone
claiming it is really working now. Might be worth asking the grub guys again.
Though presumably this would not fix the problem that switching soesn't work if
not booted with the intel gpu active, which I presume is a problem with the
i915 drm driver (but of course can be more easily "fixed" by those outb
commands in the grub config).

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