Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes: > On Mon, Jan 23, 2012 at 04:41:25PM -0800, Linus Torvalds wrote: > >> Right. I think the opportunity for problems should be pretty small. >> >> And it's not like the pty itself wouldn't continue to work - it's just >> that programs like /usr/bin/tty wouldn't be able to *find* it. >> >> Although who knows - maybe there is some other subtle interaction. > > FWIW, the subtle and nasty part in all that is that you can mknod /dev/ptmx > and it *will* work, refering to the "initial" instance. That's what > concerns me about the chroot scenarios - > mknod /jail/dev/ptmx c 5 2 > mkdir /jail/dev/pts > mount -t devpts /jail/dev/pts > chroot /jail > works fine right now, but with that change behaviour will be all wrong - > opening /dev/ptmx inside of jail will grab you a pts, all right, but > it will *not* show up in (jail) /dev/pts/* as it does with the current > kernel. > > Note that if you replace that mknod with symlink pts/ptmx /jail/dev/ptmx > the things will keep working. However, that will _only_ work for kernels > with DEVPTS_MULTIPLE_INSTANCES - without it you won't get ptmx inside > devpts (which is arguably wrong, BTW) For testing I would recommend looking at the distro chroot build cases. It looks like relatively recent udev still creates /dev/ptmx and does not create the symlink. So we might get into the awkward situation of /dev/ptmx not matching /dev/pts/ptmx with something as simple as initramfs mounting /dev/pts and then initscripts mounting /dev/pts. Eric _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
