From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Rob Landley Subject: Re: [PATCH] Fix ARCH=um segfault on x86-64. Date: Fri, 6 Mar 2009 16:20:04 -0600 References: <200903060042.19084.rob@landley.net> <20090306084848.GO22605@hack.private> <10f740e80903060150p565e9703u81d4fe47cb599ab@mail.gmail.com> In-Reply-To: <10f740e80903060150p565e9703u81d4fe47cb599ab@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Content-Disposition: inline Message-Id: <200903061620.05990.rob@landley.net> Sender: linux-kernel-owner@vger.kernel.org To: Geert Uytterhoeven Cc: =?utf-8?q?Am=C3=A9rico_Wang?= , user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org List-ID: On Friday 06 March 2009 03:50:38 Geert Uytterhoeven wrote: > On Fri, Mar 6, 2009 at 09:48, Américo Wang wrote: > > On Fri, Mar 06, 2009 at 12:42:14AM -0600, Rob Landley wrote: > >>Apparently, nobody other than me has ever attempted to use User Mode > >> Linux built from 2.6.28 on x86-64, because it doesn't work.  It still > >> doesn't work in current git.  I complained about it not working back in > >> January: > >> > >>http://sourceforge.net/mailarchive/forum.php?thread_name=200901130159.043 > >>89.rob%40landley.net&forum_name=user- mode-linux-devel > >>http://lkml.indiana.edu/hypermail/linux/kernel/0901.2/00669.html > >> > >>And today, I bothered to track down why. > >> > >>This is the commit that broke it, when Peter Anvin merged x86 and x86-64 > >> for ARCH=um: http://kernel.org/hg/linux-2.6/rev/117978 > >> > >>Here's a patch that fixes it for me: > > > > Thanks, Bob! > > I've just did a build of plain v2.6.28 on amd64 aka x86-64. The > resulting image ran fine. > > I attached my .config. Which contains: CONFIG_3_LEVEL_PGTABLES=y So the question is, why is your config saving that value, and mine isn't? Ah, I found it. You enabled CONFIG_EXPERIMENTAL, and I didn't. That's the difference. Ok, CONFIG_EXPERIMENTAL is required in order for UML to initialize its memory management. That makes a bit more sense why other people haven't seen this... Rob