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

[Dave Anderson]

Ken'ichi Ohmichi wrote:

> 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

Sounds good to me.  I don't have any plans for the translation
of the dump_level, but only a display of its value in a new "help -n"
function that I've written for diskdump dumpfiles.  "help -n" shows
netdump, ELF-diskdump, kdump, LKCD and xendump dumpfile
information, but functions for diskdump and s390 dumps were
never written.

Thanks,
  Dave