From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [RFC][PATCH 7/8]: Auto-create ptmx node when mounting devpts Date: Thu, 21 Aug 2008 10:50:26 -0700 Message-ID: <48ADAAE2.6040700@zytor.com> References: <20080821022126.GA29449@us.ibm.com> <20080821022908.GG29658@us.ibm.com> <20080821102139.43c44f67@lxorguk.ukuu.org.uk> <48AD932F.8090908@zytor.com> <20080821172700.781b0011@lxorguk.ukuu.org.uk> <48AD9C93.6080302@zytor.com> <20080821172342.GA8059@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Eric W. Biederman" Cc: kyle-hoO6YkzgTuCM0SS3m2neIg@public.gmane.org, bastian-yyjItF7Rl6lg9hUCZPvPmw@public.gmane.org, containers-qjLDD68F18O7TbgM5vRIOg@public.gmane.org, Alan Cox , xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org List-Id: containers.vger.kernel.org Eric W. Biederman wrote: >> I had the new ptmx node only in 'multi-mount' mode initially. But if users >> want the multi-mount semantics, /dev/ptmx must be a symlink. If its a symlink, >> we break in the single-mount case (which does not have the ptmx node and >> we don't support mknod in pts). > > Then have user space make it a file bind mount instead of symlink. > That should address all of the backwards compatibility concerns, and > allow us to only create it when open. The right thing is that, if you want to support back-and-forth flipping, to introduce a udev rule which looks for pts/ptmx, links to it if present, and otherwise creates the ptmx device node. This is *only* required to support back-and-forth, and can be introduced at any time after this patch is in the kernel -- or even before. -hpa