Re: [PATCH] add Altivec/VMX state to coredumps

On Sep 26, 2007, at 8:21 AM, Segher Boessenkool wrote:

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Why not put the PVR in core dumps that'd make it all easier..

PVR wouldn't be very useful...  What if you have altivec disabled ?
Also
that would mean your gdb has to know about all new processors...

Is that such a big deal? :D

Hypothetically it would be impossible to determine if you were running
on a G5 with the FPU and AltiVec turned off or an e500 core with SPE,
given the data saved.

And that is exactly as should be: a core dump represents the execution
state of a user program, it has nothing to do with the machine it was
generated on; it even is possible to restart a core dump generated on
e.g. an e500 on a 970, as long as it doesn't use facilities (e.g., SPE)
that the latter processor / execution environment doesn't provide.

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Is that a misfeature of GDB that we even have to
worry about this, or some noble plus point of a unified ISA? You
decide :)

We don't have to worry about it :-)

We should worry about it.  If one misinterprets the core file you will get unexpected behavior.  I see no reason not to do this properly and mark the sections such that its clear if its AltiVec or SPE state, rather than overloading the x86 XFPU type.

- k