From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753910AbZCFIsp (ORCPT ); Fri, 6 Mar 2009 03:48:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751258AbZCFIsg (ORCPT ); Fri, 6 Mar 2009 03:48:36 -0500 Received: from ti-out-0910.google.com ([209.85.142.187]:21223 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750761AbZCFIsf convert rfc822-to-8bit (ORCPT ); Fri, 6 Mar 2009 03:48:35 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:content-transfer-encoding :in-reply-to:user-agent; b=Zvf0MB+MeWzkBCc5YQdkkEP8qVAqczNICAUB2B5lDUSpeztNkNcXlhG/pUGxHgGqNC pztoQf3YeYm2tSGANvx2eSlEBBzcDOlxFx0uB/ro9jzM3UtBGT+Jh7lEzjP7LXC2rzNM jdnAdG8S78AoCQNbM+T5sNzF3vc+Vl2WoOp/o= Date: Fri, 6 Mar 2009 16:48:48 +0800 From: =?utf-8?Q?Am=C3=A9rico?= Wang To: Rob Landley Cc: user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Fix ARCH=um segfault on x86-64. Message-ID: <20090306084848.GO22605@hack.private> References: <200903060042.19084.rob@landley.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <200903060042.19084.rob@landley.net> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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=200901130159.04389.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! > >Signed-off-by: Rob Landley > >diff -r 178a096e9e38 arch/um/Kconfig.x86 >--- a/arch/um/Kconfig.x86 Fri Feb 27 16:49:46 2009 -0800 >+++ b/arch/um/Kconfig.x86 Thu Mar 05 23:35:55 2009 -0600 >@@ -26,9 +26,8 @@ > def_bool !X86_XADD > > config 3_LEVEL_PGTABLES >- bool "Three-level pagetables (EXPERIMENTAL)" if !64BIT >+ bool > default 64BIT >- depends on EXPERIMENTAL So, on i386, it will not depend on EXPERIMENTAL any more, right? How about changing it to the following? depends on 64BIT || EXPERIMENTAL > help > Three-level pagetables will let UML have more than 4G of physical > memory. All the memory that can't be mapped directly will be treated >>What changed is that the resulting .config no longer contains the line >"CONFIG_3_LEVEL_PGTABLES=y" (it's not visible, and thus not written out into >the config file file). Without that symbol defined, x86-64 dies trying to >boot. If you tweak the Kconfig so the symbol gets written out, it starts >working again. > >I have no idea how ANYBODY has EVER managed to use 2.6.28 User Mode Linux on >an x86-64 host. My theory is that nobody ever did. I suspect that very few >people use UML anymore now that KVM and the rustyvisor and such are available, >and those legacy users still fiddling with it are apparently all either using >old versions or 32-bit hosts. (I still like being able to stick printfs into >the kernel.) > I am sorry that I never have an x86_64 machine to use. :( -- Do what you love, f**k the rest! F**k the regulations!