Hi Vivek, 2007/03/06 12:02:46 +0530, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: >On Thu, Mar 01, 2007 at 09:15:05PM +0900, Ken'ichi Ohmichi wrote: >> >> (added Vivek Goyal) >> (added redhat-kexec-kdump-ml) >> >> Hi everyone, >> >> If Bob's proposal (the end of this mail) is merged into makedumpfile, >> the analysis behavior of ELF dumpfile is different from kdump-compressed >> dumpfile's as follows. >> When reading ELF dumpfile, the crash utility treats the excluded pages >> as zero-filled pages. But, as to kdump-compressed dumpfile, the crash >> utility will display the warning message to mean "These pages are >> excluded by partial dump" when it accesses the excluded pages. >> > >I quickly went through this thread. I don't know much about the diskdump >format but from a layman's perspective, instead of keeping the zero pages >and compressing them, why not extend diskdump format and maintain another >bitmap which signifies the valid zero pages but they are not physically >part of the core file? I think overall it might reduce dump size. Thank you for the comment. I think that it is unnecessary to extend diskdump format. Instead of having all the compressed zero-pages, it is enough that page descriptors of all zero-pages point same zero-page. In this implement, the size of dumpfile increases by only one page (4K, 16K, etc.). The attached patch is for it. >Secondly, for ELF format core files, probably we can disable the behavior of >excluding zero filled pages from dumpfile and then "crash" behavior can >be consistent. (Return zero filled page only for valid data otherwise crib). I want to use the feature of excluding zero-pages, because our systems (x86_64) have many zero-pages immediately after system booting. Bob is researching for the behavior of crash on ELF format dumpfiles. I would like to wait for his report. Thanks Ken'ichi Ohmichi
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