On Fri, Aug 29, 2014 at 06:42:18AM +0000, Atsushi Kumagai wrote: > Hello Daniel, > > >On 2013/12/10 19:41:54, kexec <kexec-bounces at lists.infradead.org> wrote: > >> > > > Did you say that dump level 2 or larger are no longer effective even for x86_64 ? > >> > > > I thought it works by the patch below, but I'm not sure about Xen. > >> > > > So I would like to know why you sent this patch. > >> > > > > >> > > > > >> > > > commit ec5b5835a113cf62a168d4a7354564a38de6b52c > >> > > > Author: ken1_ohmichi <ken1_ohmichi> > >> > > > Date: Fri Oct 9 03:05:41 2009 +0000 > >> > > > > >> > > > [v1.3.4-10] Add dump filtering on an x86_64 xen domain-0. > >> > > > > >> > > > This patch adds the dump filtering for excluding unnecessary pages (cache > >> > > > pages, user process data pages, and free pages) on on x86_64 xen domain-0. > >> > > > > >> > > > On the existing makedumpfile (v1.3.3 or former), a user could specify 0 > >> > > > or 1 only as a dump_level. By this patch, he/she can specify 2 or larger > >> > > > also as a dump_level. > >> > > > > >> > > > Now, this feature is effective on x86_64 machine only. > >> > > > >> > > Hmmm... Thanks for this. I missed this patch. However, it looks that I > >> > > do not understand something. AIUI, from Xen point of view we are not able > >> > > to use dump level higher than 1 because there is no e.g. cache pages (it > >> > > looks that we could also skip free pages but this stuff is not implemented). > >> > > Above mentioned patch suggest that there is a way to extract just only Dom0 > >> > > stuff taking into account Linux internals only. If my reasoning is true > >> > > then dump level higher than 1 is possible only if we look at Dom0 from Linux > >> > > point of view. > >> > > >> > I've reviewed the code for Xen, my understanding is the same as yours. > >> > The memory regions corresponding to hypervisor and DomU will remain even if > >> > specifying the dump level higher than 1. > >> > > >> > > However, I can not find any description how to do that. > >> > > So I am CC-ing Ken'ichi as author of this patch but I do not know that > >> > > he works for NEC still. > >> > > >> > I'm sorry but I missed your point. Did you mention a lack of description > >> > in man page about an effect when specifying the dump level higher than 1 > >> > for Xen's memory ? > >> > At least, I still think this patch is wrong because any dump level is > >> > effective for x86_64. > >> > >> Docs are not consistent because man and help displayed from makedumpfile > >> are different. Additionally, even man says nothing how to use this feature > >> on Xen vmcore file. If you use makedumpfile e.g. > >> > >> makedumpfile -Ed 2 /proc/vmcore vmcore > >> > >> it will not work because it uses VMCOREINFO_XEN instead of VMCOREINFO. > >> I discovered that if you would like to use feature from above mentioned > >> patch you must run makedumpfile in following way: > >> > >> makedumpfile -Ed 2 -x vmlinux /proc/vmcore vmcore > >> > >> Then makedumpfile will get info about dom0 directly from vmlinux. > > > >Certainly the documents should be fixed as you said, I'll do it. > > Sorry for my too late job, how about this fix ? No problem. I am busy too. I still have patch fixing this feature for new Xen versions on my long todo list. I hope that I will be able to work on it at the beginning of next year. > I'll merge it into v1.5.7 if you have no objection. Great! Thanks! > Thanks > Atsushi Kumagai > > From: Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp> > Date: Fri, 29 Aug 2014 15:11:27 +0900 > Subject: [PATCH] Fix description about filtering for Xen. > > Correct the following points for Xen dump: > > - Add how to filter the pages of domain-0. > - Fix the difference between man and help. > > Reported-by: Daniel Kiper <daniel.kiper at oracle.com> > Signed-off-by: Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp> Reviewed-by: Daniel Kiper <daniel.kiper at oracle.com> Daniel
