On Wed, Jun 19, 2024 at 03:21:42PM +0900, Masahiro Yamada wrote: > Kbuild provides scripts/Makefile.host to build host programs used for > building the kernel. Unfortunately, there are two exceptions that opt > out of Kbuild. The build system under tools/ is a cheesy replica, and > is always a disaster. I was recently poked about a problem in the tools > build issue, which I do not maintain (and nobody maintains). [1] (Side note: I hope I haven't placed undue burden on you; I understood you don't maintain tools/ and that it didn't use Kbuild. I only "poked" you because the original bug report I was replying to had you and linux-kbuild on CC already. And I appreciate your engagement, even if the bugs are due to intentional forking.) But anyway, I agree that clearer documentation and recommendations could be helpful here. To that end, some dumb questions below, as I'm not sure if this fully serves its purpose as-is: > Without a comment, somebody might believe this is the right location > because that is where objtool lives, even when a more robust Kbuild > syntax satisfies their needs. [2] > > [1]: https://lore.kernel.org/linux-kbuild/ZnIYWBgrJ-IJtqK8@xxxxxxxxxx/T/#m8ece130dd0e23c6f2395ed89070161948dee8457 > [2]: https://lore.kernel.org/all/20240618200501.GA1611012@xxxxxxxxxx/ > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > --- > > Makefile | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/Makefile b/Makefile > index 471f2df86422..ba070596ad4e 100644 > --- a/Makefile > +++ b/Makefile > @@ -1331,6 +1331,11 @@ prepare: tools/bpf/resolve_btfids > endif > endif > > +# README > +# The tools build system is not a part of Kbuild. Before adding yet another > +# tools/* here, please consider if the standard "hostprogs" syntax satisfies > +# your needs. > + Some clarifying questions / statements-as-questions: * nothing in tools/ uses Kbuild, right? (even stuff that uses KBUILD_* names is just an imitative port, right?) * not everything in tools/ is actually promoted to a high-level target, that affects this top-level Makefile. Are you only concerned about stuff that pretends to be integrated in the top-level kernel Makefile? (If not, then it seems like placing the README comments only in this Makefile is a poor choice.) * is the "standard hostprogs" recommendation a general recommendation, for all sorts of kept-in-the-kernel-tree host tools? Is the recommendation to "use Kbuild" or to "avoid putting your tool in tools/*"? Is it possible (recommended?) to plumb Kbuild stuff into tools/, even if other parts won't migrate? As is, I can't tell if this is telling people to avoid adding new stuff to tools/ entirely, or just to only add to tools/ if you're able to remain completely isolated from the rest of the kernel build -- as soon as you want to play some part in the Kbuild-covered part of the tree, you need to use Kbuild. If I'm inferring the right answers to the above, then maybe an improved wording could be something like: "The tools build system is not a part of Kbuild and tends to introduce its own unique issues. If you need to integrate a new tool into Kbuild, please consider locating that tool outside the tools/ tree and using the standard Kbuild "hostprogs" syntax instead of adding a new tools/* entry here." It's possible I'm playing mental acrobatics here in my reading too. Either way, I think this is a good trajectory: Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxxx> Regards, Brian > PHONY += resolve_btfids_clean > > resolve_btfids_O = $(abspath $(objtree))/tools/bpf/resolve_btfids > -- > 2.43.0 >
