[Crash-utility] [PATCH] debuginfo does not pick user_regs_struct on x86_64

[Wen Congyang]

At 03/02/2011 09:59 PM, Dave Anderson Write:
> 
> 
> ----- Original Message -----
>>>
>>> Right -- over the years it has been "found" in some kernel
>>> version's debuginfo data, but certainly not in all kernel
>>> versions. (mostly not)
>>>
>>> But anyway, its potential non-existence has been worked
>>> around such that the offset_table entries are not required.
>>>
>>> I did test it out on ~150 sample dumpfiles, and while it doesn't
>>> break anything, it doesn't help either -- the "bt -a" output is
>>> identical with or without the patch.
>>
>> The command "bt -a" can work fine without the patch now, because we
>> have checked it in get_netdump_regs_x86_64().
>>
>> We have a new hardware to do dump, and use makedumpfile to generate
>> vmcore. Our hardware can work when the OS is out of controll(for
>> example: dead loop). When we use crash to analyze the vmcore, bt can
>> not work, because there is no panic task.
>>
>> We have provide the value of register in the vmcore(the format is elf_prstatus,
>> it is same with normal kdump's vmcore). So I write the code to use the register
>> from notes in the vmcore when we do not find panic task. So we should know
>> these offsets. We can check it where we use, but I think it's better to check
>> and init it in x86_64_init().
> 
> Interesting -- so you essentially have an alternative dumping method
> whose format simulates a kdump.
> 
>>>
>>> Did you actually have a situation where a backtrace failed
>>> without it -- but then worked OK with your patch?
>>>
>>> And was there a reason you used "unsigned long long" declarations?
>>> I understand they are the same, but the kernel uses "unsigned long".
>>> Why the difference?
>>
>> Does this case exist: we build crash on x86 box and use it to analyze the
>> vmcore which is generate in x86_64 box? If it does not exist, I think
>> we should use "unsigend long", the same with the kernel.
> 
> No, that cannot be done.  You can build an x86 binary on an x86_64 machine
> with "make target=X86", but not the other way around.
> 
> I'll revert them to "unsigned long" declarations, and queue the patch
> for crash-5.1.3.

Thanks.

> 
> Thanks,
>   Dave
>