----- "Tokuhisa Inagaki" <tokuhisa.inagaki@xxxxxxxxxxx> wrote: > Hi, all. > > what is recommended dump level when using makedumpfile > (kdump)? I'm looking for explanation like this. > > ------------ from diskdump document -------------------- > Note that the partial dump feature has some risks. There > are memory management lists which are scanned for a page's > memory attribute, so if the list has been corrupted, the > scanning process may fail. For example, when specifying a > dump_level from 4-7 or from 12-15, the kernel's free page > linked lists are scanned; if the list is corrupt, diskdump > may hang. Furthermore, it is possible that a page type > that has been skipped may be necessary to fully investigate > the cause of some issues. Therefore, a memory collection > level should be selected to suit each situation. The > recommended level is 19, because it is easiest to determine > whether a page is zero-filled or if it is a page cache page, > and because no page lists need to be traversed. > ------------------------------------------------------- > > Does anyone know document describing these things > when using makedumpfile ? > > > Thanks, > toku. I don't know of any document for makedumpfile other than the /usr/share/doc/kexec-tools-<version>/kexec-kdump-howto.txt and the output of "makedumpfile -h". Neither of those has any caveats such as the diskdump document above, but I'm guessing that the same kind of issues would apply when makedumpfile walks page lists, the mem_map, etc. But I don't know what the failure mode would be, given that it's a user application as opposed to a kernel module. In any case, the makedumpfile maintainers are on this list and hopefully can shed some light on your query. Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
