This is the mail archive of the
gdb@sources.redhat.com
mailing list for the GDB project.
Re: [Fastboot] Re: Query: Kdump: Core Image ELF Format
- From: ebiederm at xmission dot com (Eric W. Biederman)
- To: Vivek Goyal <vgoyal at in dot ibm dot com>
- Cc: Andrew Morton <akpm at osdl dot org>, Dave Anderson <anderson at redhat dot com>, gdb <gdb at sources dot redhat dot com>, fastboot <fastboot at lists dot osdl dot org>, lkml <linux-kernel at vger dot kernel dot org>
- Date: 09 Mar 2005 07:17:49 -0700
- Subject: Re: [Fastboot] Re: Query: Kdump: Core Image ELF Format
- References: <1110286210.4195.27.camel@wks126478wss.in.ibm.com><m1br9um313.fsf@ebiederm.dsl.xmission.com><1110350629.31878.7.camel@wks126478wss.in.ibm.com>
Vivek Goyal <vgoyal@in.ibm.com> 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