[uml-devel] Generalized input

[Jeff D. <jd...@ka...>]

I've added support for specifying a variety of channel types for the serial 
line and console drivers to use to talk to the outside world.

The overall command-line syntax is 'con[nn]=[channel]' and 
'ssl[nn]=[channel]'. If the '[nn]' is present, the channel is associated with 
just the one device specified by 'nn', so you would attach console 2 to a pty 
with 'con2=pty'.  If the '[nn]' isn't there, it applies to all devices of that 
type, so 'ssl=xterm' puts every serial line in an xterm.

The channel is specified as follows:

'pty' - a host pty is allocated and the choice printed to the log.  You 
connect to the corresponding tty to talk to that device.

'xterm' - an xterm is started and all I/O with the device goes through the it.

'tty:/dev/ttyxx' - you name the tty that you want the device to attach to.  
This is useful for attaching a uml device to an unused host console.  
Attaching a device in one uml to a pty and attaching a device in another uml 
to the corresponding tty also works.  This simulates a serial line running 
between the two virtual machines.

'socket:port' - you name a port number on the host and this attaches the uml 
device to it, allowing it to be accessed from the net without needing to set 
up networking and not needing root privs for anything.  You attach to it with 
'telnet umlhost port'.  This doesn't actually work very well.  It works better 
if you do 'mode character' at the telnet command line.  But you still can't 
log in.  The reason is that telnet is sending telnet protocol across the port, 
but the getty on the other side is just interpretting it as you typing bogus 
usernames and passwords.

So, what I need, and can't find, is a telnetd that's willing to attach to a 
device rather than a port.  This would run inside UML in place of the current 
getty.  A minicom-like proggie that doesn't do protocol won't work because the 
two sides need to talk about terminal modes and stuff.  Does anyone know of 
such a beast?

What I have planned for the future is support for already-setup file 
descriptors and files.  Also, maybe support for specifying a specific pty.

I'm also going to allow specifying of input and output separately, so you 
could do something like 'con1=pty,file:/tmp/log', which would cause console 1 
to take input from a pty, but send its output to /tmp/log rather than the pty. 
 You'd be typing blind in this case, but this sort of thing is needed for 
specifying file descriptors and I'd rather implement it for everything rather 
than special-case descriptors.

Also, I'm planning on stacking channels, so 'con1=+file:/tmp/log' would log 
input and output on console 1 to /tmp/log as well as whatever other channel it 
is talking to.

This patch is available from ftp.nl.linux.org:/pub/uml/uml-latest-2.4.0-test12.
bz2 as well as from cvs.

				Jeff