H. Peter Anvin
hpa at zytor.com
Fri Aug 1 11:12:21 PDT 2008
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
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.
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