From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f172.google.com ([209.85.192.172]:35071 "EHLO mail-pf0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752772AbcIWJTz (ORCPT ); Fri, 23 Sep 2016 05:19:55 -0400 Received: by mail-pf0-f172.google.com with SMTP id s13so5984829pfd.2 for ; Fri, 23 Sep 2016 02:19:54 -0700 (PDT) Date: Fri, 23 Sep 2016 18:27:07 +0900 From: AKASHI Takahiro To: Greg KH Cc: catalin.marinas@arm.com, will.deacon@arm.com, jason.wessel@windriver.com, linux-arm-kernel@lists.infradead.org, kgdb-bugreport@lists.sourceforge.net, stable@vger.kernel.org Subject: Re: [PATCH v2 0/3] arm64: kgdb: fix single stepping Message-ID: <20160923092706.GN30248@linaro.org> References: <20160923073327.9657-1-takahiro.akashi@linaro.org> <20160923081618.GH18056@kroah.com> <20160923083257.GL30248@linaro.org> <20160923084341.GA32342@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Disposition: inline In-Reply-To: <20160923084341.GA32342@kroah.com> Sender: stable-owner@vger.kernel.org List-ID: On Fri, Sep 23, 2016 at 10:43:41AM +0200, Greg KH wrote: > On Fri, Sep 23, 2016 at 05:32:58PM +0900, AKASHI Takahiro wrote: > > On Fri, Sep 23, 2016 at 10:16:18AM +0200, Greg KH wrote: > > > On Fri, Sep 23, 2016 at 04:33:24PM +0900, AKASHI Takahiro wrote: > > > > Kgdb support on arm64 was merged in v3.15, but from its first appearance, > > > > "signle step" has never worked well. > > > > > > > > This patch fixes all the error cases I found so far. > > > > The original patch[1] was splitted into three pieces, ones for each case. > > > > patch#1, #2 should be applied to all the version, v3.15 and later. > > > > pathc#3 only for v3.16 and later. > > > > > > As this is not a regression (i.e. it has never worked), why is this > > > something for stable releases? > > > > Because, I think, that is a bug. > > The author seems to have believed that it worked. > > Please see: > > commit 44679a4f > > Author: Vijaya Kumar K > > Date: Tue Jan 28 11:20:19 2014 +0000 > > > > arm64: KGDB: Add step debugging support > > Yes, but again, it didn't work, so this would be a new feature. Yes, but again, it's a bug of kgdb on arm64 which is supposed to have been available since v3.15. > One > that obviously people aren't using in the stable kernels, otherwise they > would have noticed in the past 2 years about it being broken :) Totally agree. That is also why I've left this patch untouched for a long time. But recently a guy asked me about kgdb, saying that single step didn't work on his platform. He re-discovered this bug. He doesn't use stable kernels, but Linaro's LSK (v4.4), though :) > Please read Documentation/stable_kernel_rules.txt for the requirements > of a stable kernel patch. I don't think this series meets those rules. Please re-think about merging this patch. Thanks, -Takahiro AKASHI > thanks, > > greg k-h