From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763917AbYETNw5 (ORCPT ); Tue, 20 May 2008 09:52:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754739AbYETNwu (ORCPT ); Tue, 20 May 2008 09:52:50 -0400 Received: from [198.99.130.12] ([198.99.130.12]:39992 "EHLO saraswathi.solana.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754354AbYETNwu (ORCPT ); Tue, 20 May 2008 09:52:50 -0400 Date: Tue, 20 May 2008 09:52:38 -0400 From: Jeff Dike To: Tom Spink Cc: LKML Subject: Re: UML fails to locate address space Message-ID: <20080520135238.GB6990@c2.user-mode-linux.org> References: <7b9198260805200408k1d6b70a8xc7e4c24106e5020f@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7b9198260805200408k1d6b70a8xc7e4c24106e5020f@mail.gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 20, 2008 at 12:08:24PM +0100, Tom Spink wrote: > I've just recently pulled the latest GIT and compiled UML, however, > when I run it a message appears saying "Locating the top of the > address space... Address 0x0 no good?" and the program exits. Can you strace it and send me the output? > After some digging, it appears that page_ok is returning false when > checking 'bottom', in os_get_task_size > (arch/um/os-Linux/sys-i386/task_size.c:96). After running through > GDB, it seems that in line 31 of that file is where the segfault > occurs: > > n = *address; > > i.e. when trying to read from the address space (at address zero). The segfaults are on purpose - it will trap SIGSEGV and longjmp out of the handler and mark the affected address as not-usable. Jeff -- Work email - jdike at linux dot intel dot com