Bug#1029336: Regression: unable to mount root fs on unknown-block

[James Addison <jay@jp-hosting.net>]

Package: linux-image-6.1.0-1-rt-amd64
Severity: critical
Justification: breaks the whole system

Dear Maintainer,

When attempting to boot a ThinkPad X230 from kernel build 6.1.0-1-rt-amd64, the
following error occurs (transcribed from screen; apologies in advance for any
typos):

  [...] No filesystem could mount root, tried :
  [...] 
  [...] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
  [...] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.0-1-rt-amd64 #1  Debian 6.1.4-1
  [...] Hardware name: <disk and BIOS details>
  [...] Call Trace:
  [...]  <TASK>
  [...]  dump_stack_lvl+0x44/0x5c
  [...]  panic+0x10e/0x2db
  [...]  mount_block_root+0x1d3/0x1e6
  [...]  prepare_namespace+0x136/0x165
  [...]  kernel_init_freeable+0x25c/0x286
  [...]  ? rest_init+0xd0/0xd0
  [...]  kernel_init+0x16/0x130
  [...]  ret_from_fork+0x22/0x30
  [...]  </TASK>
  [...] Kernel Offset: 0x18600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)

This prevents the system from booting.

Adding the 'rootwait' option to the kernel commandline as mentioned in a
similar-sounding upstream bug prevents the panic, but the system pauses,
seemingly forever, without finding the filesystem to mount.

The reason that I believe this is a regression is:

 - The problem does _not_ occur for the non-rt build (6.1.0-1-amd64)
 - The problem does _not_ occur with a recent rt build (6.0.0.6-rt-amd64)

Thank you,
James