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

Bob Montgomery wrote: > On Tue, 2007-03-20 at 11:18 +0900, Ken'ichi Ohmichi wrote: > > Hi Bob, > > > > Thank you for the great report. > You are welcome. > > Before continuing the discussion of issues with proposed changes to ELF > dumpfile generation, I'd like to recap where we are and suggest a couple > of actions. > > 1) Makedumpfile patch: Ken'ichi Ohmichi's email of Wed, 7 Mar 2007 > 10:43:38 +0900 contained the patch "point_same_zero_page.patch". That > patch contains the nice solution to remove redundant zero page images > from the diskdump dump file by pointing the page descriptors of zero > pages to a common zero image. I suggest that this patch should be > applied to makedumpfile as soon as possible, without waiting on a > possible solution to the ELF situation. As described in my report, ELF > and diskdump dump files have not shown identical behavior in the past. > This patch makes diskdump dump files more accurate, and leaves ELF dump > files at the same level of accuracy that they have always had.

> With these two patches, crash reports the contents of diskdump dump > files produced by makedumpfile correctly. Zero content pages that have > not been excluded for other reasons remain accessible, and pages that > have really been excluded become inaccessible, instead of showing 0x0 > contents. Crash should continue to read old dump files as before, > because of the change in version number in the dumpfiles. > I am a little bit worried that this may cause an unnecessary abort -- based upon your experience with my suggestion of returning an error instead of a zero-filled buffer from the current compressed diskdump format -- so I may be paranoid. Anyway, I'll probably put in an "out" so that the user has the choice of getting a zero-filled buffer like it does now.