From: Matt Sealey <matt@genesi-usa•com>
To: Segher Boessenkool <segher@kernel•crashing.org>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] add Altivec/VMX state to coredumps
Date: Wed, 26 Sep 2007 15:00:28 +0100 [thread overview]
Message-ID: <46FA65FC.4000208@genesi-usa.com> (raw)
In-Reply-To: <997c015e13649d06e246d3d2c1369100@kernel.crashing.org>
Segher Boessenkool wrote:
>>>> 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.
A hypothetical question for you then..
What happens if you get a core dump for a G4 app which dynamically detects
AltiVec presence (from PVR or /proc) then crashes before AltiVec is enabled
in the kernel for that task (i.e. before any vector exception) and you run
it on your G3 and it magically carries on (maybe a race condition or so)
and causes a vector exception later?
Isn't that kind of useless? Wouldn't it?
--
Matt Sealey <matt@genesi-usa•com>
Genesi, Manager, Developer Relations
next prev parent reply other threads:[~2007-09-26 13:58 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-25 4:03 [PATCH] add Altivec/VMX state to coredumps Mark Nelson
2007-09-25 12:39 ` Kumar Gala
2007-09-25 18:00 ` Matt Sealey
2007-09-25 22:18 ` Benjamin Herrenschmidt
2007-09-26 11:05 ` Matt Sealey
2007-09-26 13:21 ` Segher Boessenkool
2007-09-26 13:32 ` Kumar Gala
2007-09-26 13:38 ` Segher Boessenkool
2007-09-26 14:00 ` Matt Sealey [this message]
2007-09-26 1:22 ` Mark Nelson
2007-09-26 3:56 ` Kumar Gala
2007-09-26 4:56 ` Mark Nelson
2007-09-26 5:37 ` Kumar Gala
2007-09-26 7:42 ` Geert Uytterhoeven
2007-09-27 2:53 ` Michael Ellerman
2007-09-27 2:48 ` Michael Ellerman
2007-09-27 10:10 ` Kumar Gala
2007-09-27 23:54 ` Michael Ellerman
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