Bug#1021918: #1021918: Kernel module blacklisting doesn't work

[Ian Jackson <ijackson@chiark.greenend.org.uk>]

Control: retitle -1 Kernel module blacklisting doesn't work
Control: tags -1 confirmed

Hi.  I just did an install of bullseye on an amd64 machine with a
troublesome wifi interface - suspected hardware fault[1].  We did
achieve a successful install, blacklisting the module for the bad
hardware, but we did encounter a version of this bug.

We edited the vmlinuz line in the installer image boot menu (we were
using the non-graphical installer) to add
  modprobe.blacklist=rtw88_8723de

The installer was able to find the USB wifi dongle we'd added, didn't
touch the cursed hardware, and ran to completion.  But, as described
in this bug report, it had created a file
  /etc/modprobe.d/blacklist.local.conf
containing just
  blacklist modprobe

I deleted this using the installer shell before rebooting into the
installed system.  The installer had *not* included anything in
GRUB_CMDLINE_LINUX.

So the troublesome hardware *wasn't* blacklisted on our reboot.
Happily nothing tried to use it.  I manually created a file
  /etc/modprobe.d/rtw88.conf
containing
  blacklist rtw88_8723de
  blacklist rtw88_8723d
and that has resulted in a working setup.

Thanks,
Ian.

[1] The fault results in periodic wifi breakage and strange symtoms
with an older Debian release.  With the bullseye installer, it causes
the installer environment to reliably hang (crashed with no response
even to capslock led).

-- 
Ian Jackson <ijackson@chiark.greenend.org.uk>   These opinions are my own.  

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