On April 19, 2016 6:24:12 PM PDT, Linus Torvalds <torva...@linux-foundation.org> wrote: >On Tue, Apr 19, 2016 at 4:29 PM, Linus Torvalds ><torva...@linux-foundation.org> wrote: >> >> I _violently_ oppose the stupid DEVPTS_MULTIPLE_INSTANCES config >option. > >So just to show what I want to actually happen, here's the hacky patch >on top of my (now merged) cleanup patch that actually does what I want >devpts to do. > >I say it's hacky, because the "follow_mount()" thing there really is >pretty hacky. Al - suggestions for how to do this *right*? > >But this actually forcibly removes the whole "newinstance" thing, and >makes every pts mount a new instance, and just relies on "ptmx" doing >the right thing. > >In other words, with this patch, you can *literally* do just this (as >root, obviously): > > mkdir test-dir > cd test-dir > > mknod ptmx c 5 2 > mkdir pts > mount -t devpts pts pts > >and after that it all just works. You can do this: > > ls -l pts > >which shows just the other ptmx noode (that is unused and pointless - >I'd actually like to just remove it, but whatever), and then you can >do > > sleep 100 < ptmx & > sleep 100 < ptmx & > ls -l pts > >and you will magically see those new 0/1 entries in that pts >subdirectory.. It's entirely independent of /dev/pts/, and there's no >magic connection or any magic dis-connection. It all JustWorks(tm). > >Note how this works even *outside* of /dev. But it works inside of >/dev equally well. > >Now, a *real* patch would > > - solve that "follow_mount()" issue some other way > > - not remove the newinstance code immediately (I did it to show that >even the bootup works with a unmodified distro) > > - actually remove the whole "DEVPTS_MULTIPLE_INSTANCES" config option > > - I'm not happy with devpts_pty_kill(). I would want to clean that up >a bit somehow. I think this is at least partly what Peter Hurley was >talking about. That thing is not pretty. > >so this attached patch is by no means meant to be applied as-is. But >it's meant to show what (a) the new organization allows and (b) what I >was going for. > > Linus
I say let's remove it unless ptmxmode= is specified. That way we don't break people who actually did the symlink thing. -- Sent from my Android device with K-9 Mail. Please excuse brevity and formatting.