[Crash-utility] enhance bt command

[Dave Anderson]

Ming Zhang wrote:
> On Mon, 2008-03-03 at 11:19 -0500, Dave Anderson wrote:
>> Ming Zhang wrote:
>>> On Mon, 2008-03-03 at 09:19 -0500, Dave Anderson wrote:
>>>> I'm not sure whether cluttering the bt -f command output would
>>>> be all that worthwhile, but I'm thinking that this request may have
>>>> some merit with respect to the "rd" command.  Currently the
>>>> "rd -s" option recognizes and translates kernel symbols that it
>>>> finds in the raw memory output.  Maybe something like a "-S"
>>>> option could do that -- plus also recognize kernel virtual memory
>>>> addresses that come from the slab cache, and alternatively display
>>>> the slab cache namestring in some recognizable manner, i.e. bracketed,
>>>> or something like to that effect.
>>>>
>>>> Then since "bt -f" displays the block of memory associated with
>>>> each stack frame, you could easily transfer the stack address
>>>> to a "rd -S [stack-address] [count]" command.
>>> yes. it will be great if we can have a rd -S!
>>>
>> Apply the attached patch and see what you think.  The "rd -S"
>> option supplements "-s" by also recognizing memory from slab
>> caches -- and alternatively displaying the slab cache name
>> in brackets.
>>
> 
> this is what it looks like
> 
>      10078b2ba30:  vprintk+498      .LC391+195657    
>      10078b2ba40:  0000000000000471 [size-32]        
>      10078b2ba50:  000000000000016e 0000000000000001 
>      10078b2ba60:  0000000000000005 [kmem_cache]     
>      10078b2ba70:  000000000000003c [size-1024]      
>      10078b2ba80:  [kmem_cache]     0000000000000000 
>      10078b2ba90:  0000000000000001 00000000801108a1 
> 
> 
> [raw value: cache name] will be better

That would take up too much space, especially on a 32-bit
machine's display, which shows 4 addresses per line.

> 
> strangely, not all the value is correct. i am looking at it.

I'm not sure what you mean by them not being correct, but
if you run "kmem -s [address]", it should show the samec
slab cache container (since it uses the same facility).
For example:

crash> rd d799df80 4
d799df80:  00000004 c0470395 d799dfa4 ca9ec8c0   ......G.........
crash> rd -S d799df80 4
d799df80:  00000004 vfs_read+159 [size-4096] [filp]
crash> kmem -s d799dfa4
CACHE    NAME                 OBJSIZE  ALLOCATED     TOTAL  SLABS  SSIZE
dff74e80 size-4096               4096        215       233    233     4k
SLAB      MEMORY    TOTAL  ALLOCATED  FREE
c64f9e20  d799d000      1          1     0
FREE / [ALLOCATED]
   [d799dfa4]
crash> kmem -s ca9ec8c0
CACHE    NAME                 OBJSIZE  ALLOCATED     TOTAL  SLABS  SSIZE
dfc7a280 filp                     192       4271      4580    229     4k
SLAB      MEMORY    TOTAL  ALLOCATED  FREE
ca9ec000  ca9ec080     20          9    11
FREE / [ALLOCATED]
   [ca9ec8c0]
crash>

Dave