Re: [PATCH bpf-next] libbpf: Add cscope and TAGS targets to Makefile

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Fri, Oct 4, 2019 at 7:36 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Fri, Oct 4, 2019 at 2:27 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> >
> > Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
> >
> > > On Thu, Oct 3, 2019 at 1:46 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> > >>
> > >> Using cscope and/or TAGS files for navigating the source code is useful.
> > >> Add simple targets to the Makefile to generate the index files for both
> > >> tools.
> > >>
> > >> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> > >> ---
> > >
> > > Thanks a lot for adding this!
> > >
> > > I tested cscope only and it works (especially without -k), so:
> > >
> > > Tested-by: Andrii Nakryiko <andriin@fb.com>
> > >
> > >
> > >>  tools/lib/bpf/.gitignore |  2 ++
> > >>  tools/lib/bpf/Makefile   | 10 +++++++++-
> > >>  2 files changed, 11 insertions(+), 1 deletion(-)
> > >>
> > >> diff --git a/tools/lib/bpf/.gitignore b/tools/lib/bpf/.gitignore
> > >> index d9e9dec04605..c1057c01223e 100644
> > >> --- a/tools/lib/bpf/.gitignore
> > >> +++ b/tools/lib/bpf/.gitignore
> > >> @@ -3,3 +3,5 @@ libbpf.pc
> > >>  FEATURE-DUMP.libbpf
> > >>  test_libbpf
> > >>  libbpf.so.*
> > >> +TAGS
> > >> +cscope.*
> > >> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> > >> index c6f94cffe06e..57df6b933196 100644
> > >> --- a/tools/lib/bpf/Makefile
> > >> +++ b/tools/lib/bpf/Makefile
> > >> @@ -262,7 +262,7 @@ clean:
> > >>
> > >>
> > >>
> > >> -PHONY += force elfdep bpfdep
> > >> +PHONY += force elfdep bpfdep cscope TAGS
> > >>  force:
> > >>
> > >>  elfdep:
> > >> @@ -271,6 +271,14 @@ elfdep:
> > >>  bpfdep:
> > >>         @if [ "$(feature-bpf)" != "1" ]; then echo "BPF API too old"; exit 1 ; fi
> > >>
> > >> +cscope:
> > >> +       (echo \-k; echo \-q; for f in *.c *.h; do echo $$f; done) > cscope.files
> > >> +       cscope -b -f cscope.out
> > >
> > > 1. I'd drop -k, given libbpf is user-land library, so it's convenient
> > > to jump into system headers for some of BPF definitions.
> >
> > Well, the reason I included it was that when using the version in the
> > kernel tree, I found it really annoying to jump to kernel headers
> > installed in the system. Then I'd rather the jump fails and I can go
> > lookup the header in the kernel tree myself.
> >
> > So maybe we should rather use -I to point at the parent directory? You
> > guys could then strip that when syncing to the github repo?
>
> -I will allow to jump into kernel repo includes, right? That would be
> even better!

Oh, and feel free to add:

Acked-by: Andrii Nakryiko <andriin@fb.com>

>
> >
> > > 2. Wouldn't this be simpler and work exactly the same?
> > >
> > > ls *.c *.h > cscope.files
> > > cscope -b -q -f cscope.out
> >
> > Well, I usually avoid 'ls' because I have it aliased in my shell so it
> > prints more info than just the file names. But I don't suppose that's an
> > issue inside the Makefile, so will fix :)
> >
> > >> +
> > >> +TAGS:
> > >
> > > let's make it lower-case, please? Linux makefile supports both `make
> > > tags` and `make TAGS`, but all-caps is terrible :)
> >
> > You mean just rename the 'make' target, right? Sure, can do...
> >
> > As for the file itself, I think the version actually on what you use to
> > generate the tags file. 'ctags' generates lower-case 'tags' by default,
> > while 'etags' generates 'TAGS'.
> >
> > I don't use either, so dunno why that different exists, and if it's
> > actually meaningful? Should we do both?
>
> Me neither, but yeah, I was referring to `make tags` target only.
>
> >
> > >> +       rm -f TAGS
> > >> +       echo *.c *.h | xargs etags -a
> > >
> > > nit: might as well do ls *.c *.h for consistency with cscope
> > > suggestion above (though in both cases we just rely on shell expansion
> > > logic, so doesn't matter).
> >
> > Heh, pedantic much? ;)
> > But OK, I have no strong feelings one way or the other...
> >
>
> Guilty as charged :) Thanks!
>
> > -Toke
> >