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From:   Ian Rogers <irogers@google.com>
Date:   Thu, 26 Jan 2023 09:50:44 -0800
Message-ID: <CAP-5=fXQXSV7yWLbnrV-KY4M=bgUwKJtn1sxH7MShz7KLNJ3yQ@mail.gmail.com>
Subject: Re: [PATCH v3 1/3] objtool: Install libsubcmd in build
To:     Josh Poimboeuf <jpoimboe@kernel.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nicolas Schier <nicolas@fjasle.eu>,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
        Stephane Eranian <eranian@google.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>
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Precedence: bulk

On Wed, Jan 25, 2023 at 5:46 PM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
>
> On Thu, Jan 05, 2023 at 01:01:53AM -0800, Ian Rogers wrote:
> > Including from tools/lib can create inadvertent dependencies. Install
> > libsubcmd in the objtool build and then include the headers from
> > there.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> > Tested-by: Nick Desaulniers <ndesaulniers@google.com>
>
> After a make, "git status" shows:
>
> Untracked files:
>   (use "git add <file>..." to include in what will be committed)
>         tools/objtool/libsubcmd/
>
> So tools/objtool/.gitignore needs an update.

Done.

> > --- a/tools/objtool/Makefile
> > +++ b/tools/objtool/Makefile
> > @@ -12,9 +12,15 @@ srctree := $(patsubst %/,%,$(dir $(CURDIR)))
> >  srctree := $(patsubst %/,%,$(dir $(srctree)))
> >  endif
> >
> > -SUBCMD_SRCDIR                = $(srctree)/tools/lib/subcmd/
> > -LIBSUBCMD_OUTPUT     = $(or $(OUTPUT),$(CURDIR)/)
> > -LIBSUBCMD            = $(LIBSUBCMD_OUTPUT)libsubcmd.a
> > +LIBSUBCMD_DIR = $(srctree)/tools/lib/subcmd/
> > +ifneq ($(OUTPUT),)
> > +  LIBSUBCMD_OUTPUT = $(abspath $(OUTPUT))/libsubcmd
> > +else
> > +  LIBSUBCMD_OUTPUT = $(CURDIR)/libsubcmd
> > +endif
> > +LIBSUBCMD_DESTDIR = $(LIBSUBCMD_OUTPUT)
>
> Similar to Nicolas' comment, it's confusing to have two variables with
> the same value.  Please s/LIBSUBCMD_DESTDIR/LIBSUBCMD_OUTPUT/

Done. I feel this is more of a meta question for the standard in the
current build. DESTDIR is related to installation, in this case header
files, OUTPUT is a build directory. Anyway, LIBSUBCMD_DESTDIR is gone
in v4.

> > +LIBSUBCMD = $(LIBSUBCMD_OUTPUT)/libsubcmd.a
> > +CFLAGS += -I$(LIBSUBCMD_OUTPUT)/include
>
> As far as I can tell, this CFLAGS addition is both ineffective (it's
> overwritten later) and unnecessary (it's made redundant by the same
> addition to the INCLUDES variable).

Agreed, removed in v4.

> --
> Josh