On Sat, May 03, 2025 at 06:39:28PM +0900, Masahiro Yamada wrote: > On Sat, May 3, 2025 at 7:54 AM Kees Cook <k...@kernel.org> wrote: > > > > v2: > > - switch from -include to -I with a -D gated include compiler-version.h > > v1: https://lore.kernel.org/lkml/20250501193839.work.525-k...@kernel.org/ > > > What do you think of my patch as a prerequisite? > https://lore.kernel.org/linux-kbuild/20250503084145.1994176-1-masahi...@kernel.org/T/#u > Perhaps, can you implement this series more simply? > > My idea is to touch a single include/generated/global-rebuild.h > rather than multiple files such as gcc-plugins-deps.h, integer-wrap.h, etc. > > When the file is touched, the entire kernel source tree will be rebuilt. > This may rebuild more than needed (e.g. vdso) but I do not think > it is a big deal.
This is roughly where I started when trying to implement this, but I didn't like the ergonomics of needing to scatter "touch" calls all over, which was especially difficult for targets that shared a build rule but may not all need to trigger a global rebuild. But what ultimately pushed me away from it was when I needed to notice if a non-built source file changed (the Clang .scl file), and I saw that I need to be dependency driven rather than target driven. (Though perhaps there is a way to address this with your global-rebuild.h?) As far as doing a full rebuild, if it had been available last week, I probably would have used it, but now given the work that Nicolas, you, and I have put into this, we have a viable way (I think) to make this more specific. It does end up being a waste of time/resources to rebuild stuff that doesn't need to be (efi-stub, vdso, boot code, etc), and that does add up when I'm iterating on something that keeps triggering a full rebuild. We already have to do the argument filtering for targets that don't want randstruct, etc, so why not capitalize on that and make the rebuild avoid those files too? So, I think the global-rebuild.h idea is a good one (though I think it should maybe be included in compiler-version.h just to avoid yet more compiler command line arguments), I'd really like to try to have the specific dependency-based way to get it done. I'll send a v3, and see what you think? -Kees -- Kees Cook
