Hi Dave, thank you for your comments. On 2024/06/24 10:52, Dave Young wrote: > Hi Kazu, > > On Wed, 19 Jun 2024 at 13:45, HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx> wrote: >> >> On 2024/06/06 3:10, Prasad Koya wrote: >>> Hi >>> >>> We use makedumpfile to read the dmesg buffer from the vmcore. We are >>> working on adding a feature to makedumpfile to extract the "process >>> list" from /proc/vmcore. Our main use case is to save the processes >>> that were running at the time of kernel crash to a file on the >>> permanent storage from the kdump kernel. We intend to read a handful >>> of useful data for each running task: pid, parent pid, real parent >>> pid, priority, nice value, RSS, VM size, command, utime, stime, OOM >>> score. >>> >>> Process list from vmcore can probably be read using crash utility, but >>> in our embedded system using makedumpfile to do that job makes sense >>> for us. >>> >>> If such an option is useful for the general users of makedumpfile, >>> we'd like to get more inputs and contribute to this feature. >> >> Hi Prasad, >> >> thank you for sharing the idea. But sorry, currently we are not >> interested in implementing such a big function in makedumpfile. >> >> The dmesg buffer is the most important information to be able to >> determine the cause of a crash only with it, so the --dump-dmesg option >> was implemented in makedumpfile first once upon a time. But now we have >> handier vmcore-dmesg command in kexec-tools, so we don't intend to add >> other functions to makedumpfile than making a dumpfile. >> >> I'm not sure whether these are doable, but I would suggest a few ideas >> instead: >> - make e.g. vmcore-process-list command like vmcore-dmesg. > > Not sure if this is worth either. I also don't think that this (dumping a process list in 2nd kernel) is worth such a (probably) big effort, because we can make a dumpfile.. I assumed that they cannot create a dumpfile, because they know that the crash-utility can read it from a vmcore. I'm not sure why makedumpfile doing it makes sense to them.. > I guess it can be done with some > crash tool scripts or a crash plugin? Yes, agree. > >> - use panic notifier to dump process list to the dmesg buffer before >> kdump, and use vmcore-dmesg to get it. > > It is not recommended to add these before kdump if people still want a > reliable kdump. Agree, a panic situation is unstable, I don't intend to recommend doing this generally. I just thought that if they cannot create a dumpfile, maybe they can make a module that uses the notifier, as a last resort. Thanks, Kazu _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
