tree 07da6329d5ba6393a99c88d2fc937cd2c132e177
parent 18ae410c930a8078d8dd2014543ce7a24d1b0011
author Luis R. Rodriguez <mcgrof@kernel.org> 1481704287 -0600
committer Luis R. Rodriguez <mcgrof@kernel.org> 1512009648 -0800

module: add debugging alias parsing support

Debugging modules can often lead to an alias question. We purposely
don't have alias parsing support upstream as this is all dealt with
in userpace with the assumption that in-kernel we just process aliases
and userspace Does The Right Thing (TM) about aliases.

Obviously userspace can be buggy though, and it can lie to us. We
currently have no easy way to determine this. Parsing aliases is
an example debugging facility we can use to help with these sorts
of problems.

You can debug by adding to your dynamic debug:

GRUB_CMDLINE_LINUX_DEFAULT="dyndbg=\"func module_process_aliases +p;\" "

Upon boot for example here a few entries:

module ext4 num_aliases: 5
alias[0] = fs-ext4
alias[1] = ext3
alias[2] = fs-ext3
alias[3] = ext2
alias[4] = fs-ext2

module xfs num_aliases: 1
alias[0] = fs-xfs

module floppy num_aliases: 3
alias[0] = block-major-2-*
alias[1] = acpi*:PNP0700:*
alias[2] = pnp:dPNP0700*

module ata_piix num_aliases: 89
alias[0] = pci:v00008086d00008C81sv*sd*bc*sc*i*
alias[1] = pci:v00008086d00008C80sv*sd*bc*sc*i*
alias[2] = pci:v00008086d00008C89sv*sd*bc*sc*i*
alias[3] = pci:v00008086d00008C88sv*sd*bc*sc*i*
... etc ...

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>