From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 28914 invoked by alias); 9 Mar 2005 14:21:31 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 28723 invoked from network); 9 Mar 2005 14:21:18 -0000 Received: from unknown (HELO ebiederm.dsl.xmission.com) (166.70.28.69) by sourceware.org with SMTP; 9 Mar 2005 14:21:18 -0000 Received: from ebiederm.dsl.xmission.com (localhost [127.0.0.1]) by ebiederm.dsl.xmission.com (8.12.3/8.12.3/Debian-7.1) with ESMTP id j29EIA9N015245; Wed, 9 Mar 2005 07:18:14 -0700 Received: (from eric@localhost) by ebiederm.dsl.xmission.com (8.12.3/8.12.3/Debian-7.1) id j29EHsDA015239; Wed, 9 Mar 2005 07:17:58 -0700 X-Authentication-Warning: ebiederm.dsl.xmission.com: eric set sender to ebiederm@xmission.com using -f To: Vivek Goyal Cc: Andrew Morton , Dave Anderson , gdb , fastboot , lkml Subject: Re: [Fastboot] Re: Query: Kdump: Core Image ELF Format References: <1110286210.4195.27.camel@wks126478wss.in.ibm.com> <1110350629.31878.7.camel@wks126478wss.in.ibm.com> From: ebiederm@xmission.com (Eric W. Biederman) Date: Wed, 09 Mar 2005 14:21:00 -0000 In-Reply-To: <1110350629.31878.7.camel@wks126478wss.in.ibm.com> Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SW-Source: 2005-03/txt/msg00084.txt.bz2 Vivek Goyal writes: > On Tue, 2005-03-08 at 11:00 -0700, Eric W. Biederman wrote: > That sounds good. But we loose the advantage of doing limited debugging > with gdb. Crash (or other analysis tools) will still take considerable > amount of time before before they are fully ready and tested. > > How about giving user the flexibility to choose. What I mean is > introducing a command line option in kexec-tools to choose between ELF32 > and ELF64 headers. For the users who are not using PAE systems, they can > very well go with ELF32 headers and do the debugging using gdb. > > This also requires, setting the kernel virtual addresses while preparing > the headers. KVA for linearly mapped region is known in advance and can > be filled at header creation time and gdb can directly operate upon this > region. I have no problems decorating the ELF header you are generating in user space with virtual addresses assuming we can reliably get that information. And before a kernel crashes looks like a reasonable time to ask that question. I don't currently see where you could derive that information. Beyond that I prefer a little command line tool that will do the ELF64 to ELF32 conversion and possibly add in the kva mapping to make the core dump usable with gdb. Doing it in a separate tool means it is the developer who is doing the analysis who cares not the user who is capturing the system core dump. But I do agree that it a use case worth solving. Eric