Features/3270: Difference between revisions

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The 3270 is the classic 'green-screen' console (see [https://en.wikipedia.org/wiki/IBM_3270 the wikipedia article]).
This information has been moved into the [https://www.qemu.org/docs/master/system/s390x/3270.html 3270 devices] chapter of the [https://www.qemu.org/docs/master/system/ QEMU System Emulation Users Guide].
 
== Code ==
* Initial posting: [https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg05216.html]
* Git: [https://github.com/cohuck/qemu/tree/3270]
 
== Implementation ==
 
The 3270 data stream is not implemented within QEMU; the code only implements tn3270 (a telnet extension; see RFCs 854 and 1576) and leaves the heavy lifting to an emulator (currently only tested with x3270).
 
== Setup ==
 
This example setup is done with a Linux guest running in an s390x-ccw-virtio machine and the x3270 emulator running on a local Linux machine.
 
=== Prereqs ===
 
==== Guest ====
 
* Make sure that 3270 support is enabled in the kernel. You'll need CONFIG_TN3270 and at least one of CONFIG_TN3270_TTY (for additional ttys) or CONFIG_TN3270_CONSOLE (for a 3270 console).
 
==== Host ====
 
* You need to apply the patches or use the [https://github.com/cohuck/qemu/tree/3270 github branch] (until the code has been integrated).
 
==== Other ====
 
* You need to have a copy of the [http://x3270.bgp.nu/ x3270 emulator] (should be packaged for most Linux distributions). Other 3270 emulators have not been tested.
 
=== Starting QEMU ===
 
* Add a tn3270 chardev to your QEMU command line (machine needs to be s390x-ccw-virtio). Example: <code>-chardev socket,id=char_0,host=0.0.0.0,port=23,nowait,server,tn3270 -device x-terminal3270,chardev=char_0,devno=fe.0.000a,id=terminal_0</code>
* Start QEMU. Your guest will be presented with a 3270 channel-attached device.
 
=== Guest Configuration ===
 
The guest will see the 3270 as a channel-attached device. With the example above, the device will show up as 0.0.000a.
 
==== Using 3270 as an additional tty ====
 
You can use the defined 3270 as an additional tty.
 
* Start the guest and log in via an alternative method (for example, via the sclp console).
* Enable the device. For the example above, use <code>chccwdev -e 0.0.000a</code>
* Find the respective device node, usually under /dev/3270/.
* Start a getty on that device node, for example via <code>systemctl start serial-getty@3270-tty1.service</code>
** You may want to defer this step until after you connected via x3270, or you won't see the banner.
 
==== Using 3270 as the console ====
 
You can use the defined 3270 as the guest's console. However, you'll usually want to use the sclp console instead.
 
* Make sure you switch the guest console to 3270. For the example above, append <code>conmode=3270 condev=000a</code> to the guest's kernel command line.
* Start the guest.
 
=== Starting the emulator ===
 
Connect x3270 to <host>:<port> (for the example above, <host>:23.
 
== Restrictions ==

Latest revision as of 08:10, 16 July 2020

This information has been moved into the 3270 devices chapter of the QEMU System Emulation Users Guide.