[Crash-utility] handling missing kdump pages in diskdump format

[Ken'ichi Ohmichi]

Hi Dave,

2007/03/29 08:31:54 -0500, Dave Anderson <anderson at redhat.com> wrote:
>Dave Anderson wrote:
>
>>
>> Can you make the vmlinux/vmcore pair available to me?  Then I
>> fix this particular issue as well as testing my implementation of the
>> crash utility's excluded page handling.
>>
>> Thanks,
>>   Dave
>
>On another note, would it be possible to pass the "dump_level" in the
>diskdump header somehow -- while maintaining backwards
>compatibility with compressed-diskdump files?  Perhaps in the
>upper bits of the diskdump->header_version, or something
>like that?
>
>I think it would be useful to know exactly which types of pages
>were excluded from a dumpfile when analyzing it.

I think it is good that the crash utility can know the dump_level
of a dumpfile. But it is not good that dump_level is merged into
diskdump->header_version, because one member should represent one
meaning. I checked the code of crash-4.0-3.21, and I noticed
diskdump->total_ram_blocks is not referred by the crash utility
though the diskdump module sets the value into it. And makedumpfile
sets 0 into it. It does not have any meaning.

Can this member be changed for dump_level ?
I think the following methods for it:
  - If the crash utility reads a dumpfile, it checks diskdump->
    header_version.
  - If diskdump->header_version is 1 or more, the crash utility
    considers diskdump->total_ram_blocks as dump_level.

By the way, the dump_level of diskdump is different from the one
of kdump (makedumpfile). If the crash utility will be able to
display the excluded page-type, we should note it. 

The dump_level of diskdump
  1: Excluding cache pages with private pages
  2: Excluding zero-filled pages
  4: Excluding free pages
  8: Excluding user process data pages
 16: Saving private pages

The dump_level of kdump (makedumpfile)
  1: Excluding zero-filled pages
  2: Excluding cache pages without private pages
  4: Excluding cache pages with private pages
  8: Excluding user process data pages
 16: Excluding free pages


Thanks
Ken'ichi Ohmichi