Re: [PATCH v2 00/21] kbuild: significantly speed up kernel builds

[Kees Cook]

On Mon, Sep 14, 2026 at 10:21:59AM +0100, Lorenzo Stoakes (ARM) wrote:
> This series makes allmodconfig builds up to 36% faster, ...

This is very nice!

> incremental builds
> up to ~70% faster, and noop builds up to ~90% faster.

Some of the changes for this seem to add complexity that I'm not sure
is balanced against the gain? I am still looking through the series,
though, maybe I'll change my opinion. ;)

> 		== allmodconfig FULL build ==

Did you try Clang CONFIG_LTO=y builds?

> 			== LLM usage ==
> [...]
> I extensively audited and rewrote a lot of it, and heavily edited commit
> messages, the cover letter and comments.

I feel like the commit logs still need a lot of work. The LLM verbosity
problem appears in many of them, for example spending 80% of the commit
log describing every step of some process as background before getting
to the actual change. I think a human writing this would be much more
terse about the background. I have, however, been known to be too terse
in my own commit logs. :P

> [...]
> Nothing too controversial was included. There are further improvements that
> could be made, but they would either by very invasive (large scale C header
> changes) or generate diminishing returns.

One area I think might solved via an LLM is the 3-pass kallsyms stuff.
If we could get a deterministic kallsyms build in 1 pass, that would be
very nice. A lot of people have tried, but it has eluded upstreaming.

-Kees

-- 
Kees Cook