imho very good idea and we'll have more and more docs there... (the only issue I see - it would be nice to have cgroups docs in the same place, though cgroups are not about namespaces directly.) Acked-By: Kirill Korotaev <dev@xxxxx> Pavel Emelyanov wrote: > Hi guys! > > As you might have seen, recently there was some spontaneous > discussion about the namespaces-working-together problems. > > Ted T'so proposed to create some document that describes what > problems user may have when he/she creates some new namespace, > but keeps others shared. I like this idea, so here's the draft > with the problems I currently have in mind and can describe > somewhat audibly - the "namespaces compatibility list". > > The Documentation/namespaces/ dir is about to contain more > docs about the namespaces stuff (e.g. I'm going to prepare > a doc about the pid namespaces, maybe Serge will want to > write something about the user namespaces development, Eric > may want to put some notes about the netns API and so on), > but currently there will be only one file. > > What would you say about it? > > Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx> > > --- > > diff --git a/Documentation/namespaces/compatibility-list.txt b/Documentation/namespaces/compatibility-list.txt > new file mode 100644 > index 0000000..4be4a3c > --- /dev/null > +++ b/Documentation/namespaces/compatibility-list.txt > @@ -0,0 +1,32 @@ > + Namespaces compatibility list > + > +This document contains the information about the problems user > +may have when creating tasks living in different namespaces. > + > +Here's the summary. This matrix shows the known problems, that > +occur when tasks share some namespace (the columns) while living > +in different other namespaces (the raws): > + > + UTS IPC VFS PID User Net > +UTS > +IPC 1 > +VFS > +PID 1 1 > +User 2 > +Net > + > +1. Both the IPC and the PID namespaces provide IDs to address > + object inside the kernel. E.g. semaphore with ipcid or > + process group with pid. > + > + In both cases, tasks shouldn't try telling this id to some > + other task living in different namespace vid shared filesystem > + or IPC shmem/message. The fact is that this ID is only valid > + within the namespace it was obtained in and may refer to some > + other object in another namespace. > + > +2. Intentionnaly, two equal user ids in different user namespaces > + should not be equal from the VFS point of view. In other > + words, user 10 in one user namespace shouldn't have the same > + access permissions to files, beloging to user 10 in another > + namespace. But currently this is not so. > > _______________________________________________ > Containers mailing list > Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx > https://lists.linux-foundation.org/mailman/listinfo/containers > _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers