Messages in this thread | | | Date | Sun, 08 Apr 2012 11:00:52 -0700 | From | "H. Peter Anvin" <> | Subject | Re: RFC: deprecating/removing the legacy mode of devpts |
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On 04/08/2012 12:30 AM, Kay Sievers wrote: > > I don't think it has much to do with udev, it follows 100% > instructions from the kernel, and it does not create the device node > that is in the way here. > > Udev does not name any device in the system since a long time. Since > quite a while it has not even the code to do mknod() and requires > devtmpfs. The device node part of udev these day is limited to manage > device node permissions and creating additional symlinks. All device > node creation happens inside the kernel itself - where it belongs - > and not in userspace. > > If the default behaviour of /dev/pts/* should be changed, the kernel > should be changed to support the multi-instance mode right away > without involving userspace. We better do not require userspace to > gain any knowledge about such stuff. I'm confident, that we should not > add more, or require to support multiple alternative ways of handling > kernel internals in userspace. > > So, I think we either remove the '/sys/class/tty/ptmx' device from the > system, and let the devpts code create the symlink in the 'devtmpfs' > filesystem, or alternatively the '/sys/class/tty/ptmx' device supports > the multi-instance mode itself, instead of requiring a symlink. Such > stuff belongs entirely into the kernel these day. Anything else seems > to just ask for trouble. >
OK, this seems very reasonable, and something that could (and probably *has to*) be done as an atomic change... maybe.
There is no way for /dev/ptmx to support the multiinstance mode since it is located outside any devpts filesystem; it *has* to be inside the devpts filesystem in order to function... if that wasn't the case this whole thing would have been trivial from the get-go.
Greg, do you have any insights in what would have to be necessary mechanics to make this.
-hpa
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