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From:   Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Date:   Wed, 1 May 2019 16:41:15 -0400
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Vineet Gupta <Vineet.Gupta1@synopsys.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        lkml <linux-kernel@vger.kernel.org>,
        "linux-perf-users@vger.kernel.org" <linux-perf-users@vger.kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        arcml <linux-snps-arc@lists.infradead.org>
Subject: Re: perf tools build broken after v5.1-rc1
Message-ID: <20190501204115.GF21436@kernel.org>
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Em Tue, Apr 30, 2019 at 06:12:35PM +0200, Arnd Bergmann escreveu:
> On Mon, Apr 29, 2019 at 7:17 PM Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote:
> >
> > On 4/22/19 8:31 AM, Arnaldo Carvalho de Melo wrote:
> > >> A quick fix for ARC will be to create our own version but I presume all existing
> > >> arches using generic syscall abi are affected. Thoughts ? In lack of ideas I'll
> > >> send out a patch for ARC.
> > >>
> > >> P.S. Why do we need the unistd.h duplication in tools directory, given it could
> > >> have used the in-tree unistd headers directly ?
> > > I have to write down the explanation and have it in a file, but we can't
> > > use anything in the kernel from outside tools/ to avoid adding a burden
> > > to kernel developers that would then have to make sure that the changes
> > > that they make outside tools/ don't break things living there.
> >
> > That is a sound guiding principle in general but I don't agree here. unistd is
> > backbone of kernel user interface it has to work and can't possibly be broken even
> > when kernel devs add a new syscall is added or condition-alize existing one. So
> > adding a copy - and deferring the propagation of in-kernel unistd to usersapce
> > won't necessarily help with anything and it just adds the burden of keeping them
> > in sync. Granted we won't necessarily need all the bleeding edge (new syscall
> > updates) into that header, its still more work.
> 
> I think more importantly, it seems completely broken to sync a file from
> asm-generic but not the arch specific file that includes it.
> 
> The 1a787fc5ba18ac7 commit copied over the changes for arm64, but
> missed all the other architectures changed in c8ce48f06503 and the
> related commits.

Right, I have a patch copying the missing headers, and that fixed the
build with the glibc-based toolchain, but then broke the uCLibc one :-\

I'm travelling, so coulnd't get back to this, will try as possible.

- Arnaldo