Re: Christmas list for the kernel

Bill Davidsen
2005-11-28T19:13:39Z

Vojtech Pavlik wrote:
> On Wed, Nov 23, 2005 at 11:37:23AM -0500, Jon Smirl wrote:
>
>
>>Before everyone gets excited, I realize that all of this has
>>historical implications. But that doesn't mean we can't discuss
>>possible future alternative solutions.
>>
>>Thinking about this for a while it seems to me that the problem is
>>that the various apps (init, syslog) etc should not have a tty name as
>>part of their command line parameters. Instead these apps could use
>>ptys instead. Ptys would solve all of the race problems too.
>>
>>Is there any good reason (other than history) for using a device node
>>name (tty0, etc) instead of some other naming scheme if names are
>>needed at all?
>>
>>If init, syslog, etc can be converted to ptys, do we need ttys? Xterms
>>use ptys I don't notice that they aren't connect to a fix tty name.
>>The virtual consoles would still be 0,1,2 but do they have to be
>>hooked to tty0, 1, 2 instead of a pty?
>
>
> The basic difference between a pty and tty is that a pty connects to a
> program (that created it by opening the ptmx node, for example xterm or
> ssh) on the other end, while a tty connects to the kernel doing all the
> character drawing in the framebuffer.
>
> You can't easily use one instead of the other, they're very different
> beasts.
>
> Of course, a way to use a pty would be to have the console
> implementation in userspace.
>
> The fact that no program is on the other end of a tty is also the reason
> why they cannot be created dynamically like ptys, there is noone to open
> a "ttmx" to create the ttys.
>
> Hence, the device nodes are pre-created by the kernel, while the real
> devices are only created on open.
>
Thank you, you can omit answering my previous post if you like, I can
understand ugly but necessary.

--
-bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me