Quoting Nick Andrew ([EMAIL PROTECTED]): > On Fri, Feb 22, 2008 at 04:14:12PM -0600, Serge E. Hallyn wrote: > > Quoting Nick Andrew ([EMAIL PROTECTED]): > > > config UTS_NS > > > bool "UTS namespace" > > > depends on NAMESPACES > > > help > > > - In this namespace tasks see different info provided with the > > > - uname() system call > > > + Enable support for multiple UTS system attributes. > > > + > > > + Each UTS namespace provides an individual view of the > > > + information returned by the uname() system call including > > > + hostname, kernel version and domain name. > > > + > > > + This is used by container systems (e.g. vservers) so that > > > + each container has its own hostname and other attributes. > > > + Tasks in the container are placed in the UTS namespace > > > + corresponding to the container. > > > > this paragraph reads a little weird... really what happens is that > > each forked task is in the same UTS namespace as its parent, unless > > it was cloned with CLONE_NEWUTS or has done unshare(CLONE_NEWUTS), > > in which case it receives a copy. > > You mean only the third paragraph, right? I hope the other two are > accurate. > > I'm trying to describe how the feature is used by container systems > and my description is obviously inaccurate. There are subtle semantic > differences between the way the different namespaces work, which you've > pointed out. I think mentioning CLONE_NEWUTS or other flags is too > technical for help descriptions. > > For UTS_NS and IPC_NS I think I could remove that paragraph because > the end user hint "Answer Y if you will be using a container system" > remains. For USER_NS and PID_NS however, these features are tagged > EXPERIMENTAL so the hint is "If unsure, say N" and I think I need > to at least mention the use in container systems or find some better > clarifying description which doesn't get too technical. > > > > + This is used by container systems (e.g. vservers). > > > + Tasks in the container are placed in the IPC namespace > > > + corresponding to the container. > > > > Same as with UTS, except that upon CLONE_NEWIPC the task receives a > > blank new ipc namespace, not a copy of the original. > > Per above my response is to remove the paragraph. > > > > config PID_NS > > > [...] > > > default n > > > depends on NAMESPACES && EXPERIMENTAL > > > help > > > - Suport process id namespaces. This allows having multiple > > > - process with the same pid as long as they are in different > > > - pid namespaces. This is a building block of containers. > > > + Enable experimental support for hierarchical process id namespaces. > > > > > > - Unless you want to work with an experimental feature > > > - say N here. > > > + This is a function used by container-based virtualisation > > > + systems (e.g. vservers). Each process will have a distinct > > > + Process ID in each PID namespace which the process is in. > > > + Processes in the container are placed in the PID namespace > > > + corresponding to the container, and cannot see or affect > > > + processes in any parent PID namespace. > > > > A cloned process inherits the pid namespace hierarchy from its > > parent. If it was cloned with CLONE_NEWPID, the hierarchy is > > topped with one additional newly created pid namespace. This > > is the only pid namespace in which the new process will be able > > to see processes, while it will be visible in all namespaces in > > its pidns hierarchy. > > Yes, I understand that. Would you agree that your problem is with the > wording "Processes in the container are placed in the PID namespace > corresponding to the container"? And that this is the part that needs > to be fixed?
Yup. thanks, -serge > ... todo = revisit these descriptions soon, not today though > > Nick. > -- > PGP Key ID = 0x418487E7 http://www.nick-andrew.net/ > PGP Key fingerprint = B3ED 6894 8E49 1770 C24A 67E3 6266 6EB9 4184 87E7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
