[Crash-utility] [RFC 0/4] Add support to extract hardware device dumps from vmcore

[Surendra Mobiya]

Hi Dave,

On Saturday, April 04/13/19, 2019 at 00:39:09 +0530, Dave Anderson wrote:
> 
> Hi Surenda,
> 
> Great -- I've been looking forward for this patch set to arrive.
> 
> A couple things...
> 
> First, I'm going to need two sample vmcores (one ELF, one compressed kdump)
> along with the associated vmlinux.  You can contact me off-list with details
> on how we can arrange a transfer.
> 
> Second, I do not want to add a new command.  I rarely do so -- in fact, 
> the only times since the original crash utility was released was in 2012,
> when the "ipcs" and "tree" commands were added in crash-6.0.7 and crash-6.0.8.
> New functionality is typically added as an option to an existing command.
> And in this case, the natural location to put it is in the existing "dev" 
> command, and the devdump_extract() function can be moved into dev.c.
> (FWIW, you can add your Chelsio copyright at the top of that file)
> 

Ok, thanks for the suggestion. We will move the logic to dev command,
instead.

We're thinking along the lines of following sample commands:

Display the available device dumps
crash> dev -v
INDEX                         NAME                      OFFSET            SIZE
0                      cxgb4_0000:02:00.4               0x278             33558464
1                      cxgb4_0000:03:00.4               0x2001278         33558464

Extract device dump at specified index
crash> devdump -v 0 -f device_dump_0.bin
33558464 bytes copied from 0x278 to device_dump_0.bin

Let us know your thoughts.

> Third, there are some aesthetic changes that should be made in order
> to have the display use a more traditional output format like those
> used by other commands, e.g., with a single header with NAME, OFFSET and 
> SIZE columns.
> 

Ok, We will fix this in next version.

> Other than that, this looks good on paper!
> 
> Thanks,
>   Dave
> 

Thanks
Surendra


> 
> ----- Original Message -----
> > When kernel panic happens and kdump crash kernel is loaded, device
> > drivers enabled in the kdump crash kernel collect device specific
> > snapshot of the hardware/firmware state of their underlying devices.
> > These snapshots are exported as ELF notes with note type NT_VMCOREDD
> > (i.e., 0x700) in vmcore [1].
> > 
> > This series of patches enhance crash utility to analyze and
> > extract these hardware specific device dumps from vmcore using
> > a new "devdump" command.
> > 
> > Patches 1 and 2 enhance help -D to parse NT_VMCOREDD ELF notes
> > in ELF vmcore and KDUMP vmcore, respectively.
> > 
> > Patches 3 and 4 implement devdump command to analyze and extract
> > hardware specific device dumps from ELF vmcore and KDUMP vmcore,
> > respectively.
> > 
> > Suggestions and feedback will be much appreciated.
> > 
> > Thanks,
> > Surendra
> > 
> > [1] https://lkml.org/lkml/2018/5/2/190
> > 
> > Surendra Mobiya (4):
> >   parse NT_VMCOREDD ELF notes in ELF vmcore
> >   parse NT_VMCOREDD ELF notes in KDUMP vmcore
> >   add devdump command to extract NT_VMCOREDD from ELF vmcore
> >   enhance devdump command to extract NT_VMCOREDD from KDUMP vmcore
> > 
> >  Makefile      |   4 +--
> >  defs.h        |  16 +++++++++
> >  devdump.c     | 114
> >  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  diskdump.c    |  71 +++++++++++++++++++++++++++++++++++-
> >  global_data.c |   1 +
> >  help.c        |  23 ++++++++++++
> >  memory.c      |   7 ++++
> >  netdump.c     |  89 +++++++++++++++++++++++++++++++++++++++++++--
> >  netdump.h     |   3 ++
> >  vmcore.h      |  36 +++++++++++++++++++
> >  10 files changed, 359 insertions(+), 5 deletions(-)
> >  create mode 100644 devdump.c
> >  create mode 100644 vmcore.h
> > 
> > --
> > 1.8.3.1
> > 
> >