[Crash-utility] enhance bt command

[Dave Anderson]

Ming Zhang wrote:
>> OK I understand.  Yeah, it's always worked that way -- I don't recall
>> why other than the fact that by the time the address is displayed, the
>> function that does the display no longer has a handle on the beginning
>> address of the object, only the "requested" address, the slab it came
>> from, whether it's free/allocated, and whether it's sitting on a per-cpu
>> cache.  I'll have to revisit that sometime...
> 
> thanks for putting that on your todo list.
> 
> 
> so will you check in the patch soon?

I'll queue it for the next release, whenever that is.  Typically if nothing
serious breaks in the meantime, I do it about once a month.

>>>> If you want to look at all of the objects in a slab represented
>>>> as data structures, you're going to have supply the knowledge of
>>>> what data structure they are.  It's simple enough, just do a "kmem -S"
>>>> into a file, delete everything except the object addresses that you're
>>>> interested in, insert "struct whatever" in front of each address, save
>>> this is exactly what i did when i have to do work like this by using
>>> gawk, tr, and grep.
>>>
>>>> the file -- and run it as crash input file.
>>>>
>>> how to do this? i know crash -i can run a file at beginning. but how to
>>> run command in a file at any moment?
>>>
>> Enter "help input" -- where it talks about "<":
> 
> 
> thanks for the hint. you save me quite a lot key strokes!
> 
> 
> thanks again for all the help!