Re: [PATCH] init/main: Expose built-in initcalls and blacklist status via debugfs

[Andrew Morton <akpm@linux-foundation.org>]

On Sun, 10 May 2026 02:13:01 -0400 Aaron Tomlin <atomlin@atomlin.com> wrote:

> At present, identifying the correct function name to supply to the
> "initcall_blacklist=" kernel command-line parameter requires manual
> inspection of the source code or kernel symbol tables. Furthermore,
> administrators lack a reliable runtime mechanism to verify whether a
> specified built-in module has been successfully blacklisted.

I expect nobody has felt a need for this in their day-to-day work, so
the interest is low.

A detailed description of the use-cases would be of benefit - help
people better understand the value of this to our users.  I suggest you
add this info and send a v2, if motivated.

> To resolve this, introduce a new debugfs interface at
> /sys/kernel/debug/modules/builtin_initcalls. This file enumerates all
> built-in modules alongside their corresponding initialisation callbacks
> (e.g., those specified by module_init()) in a simple format:
> "module_name init_callback".

Isn't this information all available at build time?

Can we extract it and put it in some file somewhere which becomes part
of the distributed kernel package?

Or is it possible to write some userspace application which processes
the files which are typically in the kernel package and which extracts
this info?

> If a built-in module has been actively
> blacklisted, the entry is explicitly appended with a " [blacklisted]"
> suffix.

Can this be added to the /proc/modules output in some fashion?  Perhaps
just add TAINT_BLACKLISTED and we get this info almost for free?