From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756974AbbE2RtN (ORCPT <rfc822;w@1wt.eu>);
	Fri, 29 May 2015 13:49:13 -0400
Received: from mail-la0-f41.google.com ([209.85.215.41]:34818 "EHLO
	mail-la0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1756423AbbE2Rry (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Fri, 29 May 2015 13:47:54 -0400
MIME-Version: 1.0
In-Reply-To: <20150528131743.GA9496@gmail.com>
References: <5566EBE7020000780007E659@mail.emea.novell.com>
 <20150528090133.GA469@gmail.com> <5566FFDD020000780007E711@mail.emea.novell.com>
 <20150528112017.GA28196@gmail.com> <55671D63020000780007E885@mail.emea.novell.com>
 <20150528131743.GA9496@gmail.com>
From: Andy Lutomirski <luto@amacapital.net>
Date: Fri, 29 May 2015 10:47:31 -0700
Message-ID: <CALCETrWw0hogKsf3wO5aYeuJB0j5-wE5Hzm4==X5bJsbZNiY3g@mail.gmail.com>
Subject: Re: [PATCH] x86/debug: Remove perpetually broken, unmaintainable
 dwarf annotations
To: Ingo Molnar <mingo@kernel.org>
Cc: Jan Beulich <JBeulich@suse.com>, Borislav Petkov <bp@alien8.de>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>, Ingo Molnar <mingo@elte.hu>,
        Brian Gerst <brgerst@gmail.com>,
        =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, May 28, 2015 at 6:17 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Jan Beulich <JBeulich@suse.com> wrote:
>
>> > and meanwhile you can keep a revert of this patch ported to SUSE kernels in
>> > whatever fashion you prefer.
>>
>> Funny suggestion - I don't think that's reasonable for us to do. Or if we were
>> to, we could as well invest in doing the re-work you're asking for; I don't
>> think anyone will have the time to do either.
>
> That's fair enough: if there's not enough resources to keep a feature maintainable
> upstream then it should not be upstream in that form.
>
> This isn't just some driver we can let bit-rot in peace until it finds a
> maintainer (or not), without affecting anyone but users of that driver.
>
> This is hundreds of usage sites of ugly code intermixed with critical pieces of
> assembly code that negatively affects the hackability of everything.
>
> Also, with the feature missing completely, maybe someone finds a method to
> introduce it in a maintainable fashion, while with the feature included upstream
> there's very little pressure to do that. As a bonus we'd also win a workable dwarf
> unwinder.

Before doing something drastic like this, I think we should get Josh's
opinion, since I think he's working on a new (?) unwinder.

FWIW, musl is considering some kind of automatic annotation scheme:

http://www.openwall.com/lists/musl/2015/05/13/5

--Andy