On Thu, Jun 13, 2024 at 11:17:47AM +0200, Peter Zijlstra wrote: > On Thu, Jun 13, 2024 at 07:38:51AM +0200, Greg Kroah-Hartman wrote: > > On Wed, Jun 12, 2024 at 03:30:24PM -0700, Boqun Feng wrote: > > > +// Generated by scripts/atomic/gen-rust-atomic-helpers.sh > > > +// DO NOT MODIFY THIS FILE DIRECTLY > > > > Why not just build this at build time and not check the file into the > > tree if it is always automatically generated? That way it never gets > > out of sync. We do this for other types of auto-generated files in the > > kernel today already. > > Part of the problem is, is that a *TON* of files depend on the atomic.h > headers. If we'd generate it on every build, you'd basically get to > rebuild the whole kernel every single time. > > Also, these files don't change too often. And if you look, there's a > hash in those files which is used to check if things somehow got stale. That and: 1) The generation is currently slow (multiple seconds), which gets people angry if they have to wait for it for a clean build. Improving that would require changing the way we generate the headers (e.g. rewrite that in something else to avoid the subshell fork problem). Last I looked there wasn't an obvious better way to do this, because nice options ended up pulling in more build-time dependencies. 2) Linus wanted git grep to work, which meant checking in the generated files: https://lore.kernel.org/all/CA+55aFxjU0op8QLLu0n-RjHBs7gQsLvD8jcyedgw6jeZFN7B+Q@xxxxxxxxxxxxxx/ Mark.
