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Re: [PATCH] Add --core-pattern option to eu-stack
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Thu, 27 Nov 2014 22:27:11 +0100
- Subject: Re: [PATCH] Add --core-pattern option to eu-stack
On Thu, 27 Nov 2014 12:04:39 +0100, Mark Wielaard wrote:
> On Wed, 2014-11-26 at 15:32 +0100, Jan Kratochvil wrote:
> > Therefore they are dead at the core_pattern time, they cannot be ptraced and
> > therefore they cannot be unwound. One could only find them in the core file
> > itself but that is outside of the scope of this eu-stack feature.
> Why do you think that is out of scope? We get both the actual tid
> through the command line option and the core file through stdin. Can't
> we combine those two to get all information we want/need?
It could be extended that way but:
Currently elfutils is used only for the list of unwound PCs. There is missing
a big part of functionality present in GDB - displaying parameters, local
variables, entry-value recovered values, data types pretty printing etc.
And I have doubts unwind of non-crashed threads is useful at all.
It is a new functionality on top of this patch that it has to read thread
registers from PT_NOTE but access the memory via ptraced crashed thread.
Fortunately core file PT_NOTE is first so it can be read quickly:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
NOTE 0x0004a0 0x0000000000000000 0x0000000000000000 0x0005f4 0x000000 0
As reading the whole core file is in many times not possible (without some
better kernel core dumping interface):
-fsanitize=address locks up abrt-hook-ccpp
So I agree your proposal makes some sense but:
* I find it an incremental feature on top of this one.
* Given elfutils just lists the unwound PCs I do not see how it is useful.
What is your - or Martin's - opinion on such feature given these contraints?