[Crash-utility] dev command deteriorates with new kernels

[Bob Montgomery]

On Mon, 2009-06-08 at 20:37 +0000, Dave Anderson wrote:
> ----- "Bob Montgomery" <bob.montgomery at hp.com> wrote:
> 
> > When I tried the dev command and it bombed at the chrdev stuff before
> > getting to the blkdev stuff, I was motivated to get it going enough to
> > see if it would help answer my question, but it doesn't print anything
> > (like hd_struct pointers) that could help me with my problem.  But I
> > figured someone had once wanted that device info, so it might as well
> > work...
> 
> Re: your quest to find an hd_struct, perhaps the command could be made a
> bit more useful in that respect as well.
> 
> For character devices, the cdev_map.probes[255] probe structure's
> "data" field points to a cdev structure, where the file_operations 
> pointer is found.
> 
> For block devices, the bdev_map.probes[255] probe structure's
> "data" field points to a gendisk structure, where the file_operations 
> pointer is found.  But the gendisk structure also has an embedded
> hd_struct, which is presumably what you were looking for?
> 
> If that's the case, then maybe the command should display the address 
> of the cdev or gendisk structures associated with the device?
> 
> Dave

That would certainly make the command a lot more useful for digging
around.  I ended up using "list -o 0xa0 -H all_bdevs -s block_device"
and pulling the (struct hd_struct *)bd_part field out of all the struct
block_device's in the list.  By doing that I eventually found 3
hd_structs for partition 0, 1, and 5 of the disk of interest.  The
gendisk struct for the disk would give me the part0 hd_struct and the
part_tbl pointer should get me to all the others.  That would be a lot
easier.

Thanks,
Bob Montgomery