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Re: port-xen/49869: Xen DomU fails to crash dump

On Sat, May 02, 2015 at 07:50:00AM +0000, wrote:
> >Description:
> Neither a i386 nor a amd64 DomU are able to dump core after a system
> panic.
> amd64 provides an empty memory map (dumpsize = 0) to the dump functions.
> These will then just abort with the message "not possible".
> i386 panics when you try to run the 'sync' command in ddb.

this is a known issue. From memory, the problem is with the pa -> ma
translation. This may be fixable without too much work, but then there
woukd be another problem:
the MI dump functions (and also /dev/mem) uses PA addresses
as offsets, but some pointers (including the page tables) uses MA
addresses. This basically means that the dump would be unusable.
This is not easy to fix and would require changes to the crash
dump analysis tools.

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference

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