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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 20 Apr 2020 12:21:46 -0700
Message-ID: <CAHk-=wg6QqiaLqk19nLLAjLFNf8eY7d1m2-Qigg9w3H6iGu+EQ@mail.gmail.com>
Subject: Re: [GIT pull] perf/urgent for 5.7-rc2
To:     Josh Poimboeuf <jpoimboe@redhat.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "the arch/x86 maintainers" <x86@kernel.org>
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On Mon, Apr 20, 2020 at 11:17 AM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> If you added something bad to a file, and just rebuilt that file, you
> wouldn't see the objtool warning until later when you build the entire
> kernel.

Yes, that's not optimal, but I think I'd personally still prefer that
behavior. Especially since I seldom build single files, and in fact
rather seldom build without some "make -j32" or similar: so build
errors don't happen linearly in the first place.

> (Of course the same complaint would apply to vmlinux.o
> validation.)  But the warning shows the .o file, which could be
> confusing.

The warning should show the proper loe-level *.o file, so I don't see
what's confusing about that.

Yes, the error would happen while trying to link (say)
kernel/built-in.a, and 'make' would report that creating that archive
had failed, but 'objtool' itself would report the particular object
file it was working on that had issues.

So the errors should be pretty obvious. But like PeterZ, the makefile
magic escapes me.

            Linus