Re: xm dump-core and analyzing

[John Levon <levon@movementarian.org>]

On Mon, Dec 11, 2006 at 11:47:25AM -0500, Dave Anderson wrote:

> Cool right back at you!
> 
> Nothing would make me happier than to see the xendump format
> replaced by an ELF format vmcore -- as long as I can make the
> p2m translations.

Seconded (thirded?). ELF is a perfect format for this since it's
extendable and naturally understood by the debuggers we all have.

> I "get by" now with paravirtualized x86/x86_64 writeable page table kernels
> because even though there are holes in the array of mfn's with respect
> to their associated pfn's in the xendump file, I can:
> 
> (1) take the machine address of the cr3 from the xendump header,
> (2) walk the (writeable) page tables to find the "phys_to_machine_mapping" symbol,
> (3) read what's there, and then re-create the phys_to_machine_mapping[] array of the
>      dumped kernel.
> 
> And from that point on, all p2m translations can be made by looking at that
> re-created table for the mfn associated with any pfn, and then looking up
> the mfn in the xendump corefile.

How do you know what address that symbol is at? It's a requirement for
us that the dump is completely stand-alone. Ideally we would get this
issue fixed for 3.0.4, but I haven't found time to work on the full fix
that Keir suggested :/

regards
john