From: "H. Peter Anvin" <hpa@zytor.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: sukadev@us.ibm.com, Andrew Morton <akpm@osdl.org>,
serue@us.ibm.com, matthltc@us.ibm.com,
Pavel Emelyanov <xemul@openvz.org>,
Containers <containers@lists.osdl.org>,
linux-kernel@vger.kernel.org, Alan Cox <alan@lxorguk.ukuu.org.uk>,
Greg KH <greg@kroah.com>
Subject: Per-instance devpts
Date: Fri, 01 Aug 2008 11:12:21 -0700 [thread overview]
Message-ID: <48935205.3090807@zytor.com> (raw)
In-Reply-To: <1208027215.28187.17.camel@x61.ebiederm.org>
Since the issue of PTY namespaces came up (and was rejected) back in
April, I have thought a little bit about changing ptys to be tied
directly into a devpts instance. devpts would then be a "normal"
filesystem, which can be mounted multiple times (or not at all). pty's
would then become private to a devpts instance.
This is what it would appear would have to change, and I'd like to get
people's feeing for the user-space impact:
1. /dev/ptmx would have to change to a symlink, ptmx -> pts/ptmx.
2. Permissions on /dev/ptmx would not be persistent, and would have to
be set via devpts mount options (unless they're 0666 root.tty, which
would presumably be the default.)
3. The /proc/sys/kernel/pty limit would be global; a per-filesystem
limit could be added on top or instead (presumably via a filesystem
mount options.)
I worry #1 would have substantial user-space impact, but I don't see a
way around it, since there would be no obvious way to associate
/dev/ptmx with a filesystem.
-hpa
next prev parent reply other threads:[~2008-08-01 18:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-12 17:29 [PATCH 0/4] Helper patches for PTY namespaces sukadev
2008-04-12 17:32 ` [PATCH 1/4]: Propagate error code from devpts_pty_new sukadev
2008-04-12 17:32 ` [PATCH 2/4]: Factor out PTY index allocation sukadev
2008-04-12 17:33 ` [PATCH 3/4]: Move devpts globals into init_pts_ns sukadev
2008-04-12 17:34 ` [PATCH 4/4]: Enable multiple mounts of /dev/pts sukadev
2008-04-12 18:09 ` [PATCH 0/4] Helper patches for PTY namespaces H. Peter Anvin
2008-04-12 18:35 ` Al Viro
2008-04-12 18:54 ` Multiple instances of devpts H. Peter Anvin
2008-04-12 19:15 ` Eric W. Biederman
2008-04-12 19:24 ` H. Peter Anvin
2008-04-12 19:30 ` H. Peter Anvin
2008-04-12 19:06 ` [PATCH 0/4] Helper patches for PTY namespaces Eric W. Biederman
2008-04-13 0:59 ` Serge E. Hallyn
2008-08-01 18:12 ` H. Peter Anvin [this message]
2008-08-01 19:23 ` Per-instance devpts Dave Hansen
2008-08-01 19:35 ` Al Viro
2008-08-01 19:37 ` H. Peter Anvin
[not found] ` <f73f7ab80808020004j15b0d0e5x5fa911242641b34d@mail.gmail.com>
2008-08-02 7:06 ` Kyle Moffett
2008-08-02 15:33 ` H. Peter Anvin
2008-08-02 8:54 ` Bastian Blank
2008-08-03 5:08 ` sukadev
2008-08-03 11:31 ` H. Peter Anvin
2008-08-03 12:04 ` Alan Cox
2008-08-03 17:46 ` sukadev
2008-08-03 17:54 ` Alan Cox
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