[Crash-utility] Re: crash 4.0.9 on x86 is crashing

[Dave Anderson]

----- "Sumeet Gupta" <meetsumeet at gmail.com> wrote:

> Hi,
> 
> It was my mistake.
> 
> During an earlier debugging, I set verbose=1, misinterpreting it to
> mean just a few debug prints.

What do you mean by that?  Where are you setting "verbose"?

> On restoring the code, I'm able to run crash utility quite well. I'm
> yet to understand the purpose of verbose, though.

Right -- nor do I.  Regardless, I don't know why you should have run
into that problem on that particular symbol.  If you can make that
vmcore available for me to download, I can take a look at it.  

> 
> On a side-topic - is an ARM port of this utility (ie, a vmcore
> generated on an ARM system, debugged with crash offline on X86)
> available, or in the offing?

None that I'm aware of.  It was brought up on this list some time
ago, and I gave the requester some initial guidance on the steps
to take in order to add support for a new architecture.  But I've
heard nothing since then.

Dave


> 
> Sumeet
> 
> 
> On Tue, Sep 29, 2009 at 7:03 AM, Sumeet Gupta < meetsumeet at gmail.com >
> wrote:
> 
> 
> 
> 
> 
> Hi All,
> 
> I downloaded and built crash 4.0.9 for Intel X86 linux machine.
> I'm trying to debug kdump-generated vmcore, taken using the "crash
> kernel".
> Kernel: 2.6.27.34
> Main kernel argument: crashkernel=64M at 16M
> Main kernel loaded at 2M.
> 
> The problem:
> ./crash <vmlinux> <vmcore>
> behaves kinda strange... it gets stuck in the following loop of
> function calls, during reading totalram_pages symbol:
> get_symbol_data("totalram_pages") -> readmem("totalram_pages") ->kvtop
> -> x86_kvtop ("pgd page") ->readmem ("pgd page") ->kvtop ->
> x86_kvtop("pgd page") -> readmem("pgd page")
> 
> 
> and eventually crashes, probably when recursion reaches stack limit.
> 
> Why would such a situation happen...?
> 
> With gdb, though, things are different - gdb is able to read the
> vmcore, and give the gdb prompt, at which I can see the init_mm
> structure, and backtrace etc. I also verified that pgd address
> (init_mm.pgd) is the same as crash is trying to read through
> readmem("pgd page").
> 
> 
> Any inputs will be very useful.
> 
> Thanks,
> Sumeet
> 
> 
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