| 3270 devices |
| ============ |
| |
| The 3270 is the classic 'green-screen' console of the mainframes (see the |
| `IBM 3270 Wikipedia article <https://en.wikipedia.org/wiki/IBM_3270>`__). |
| |
| The 3270 data stream is not implemented within QEMU; the device only provides |
| TN3270 (a telnet extension; see `RFC 854 <https://tools.ietf.org/html/rfc854>`__ |
| and `RFC 1576 <https://tools.ietf.org/html/rfc1576>`__) and leaves the heavy |
| lifting to an external 3270 terminal emulator (such as ``x3270``) to make a |
| single 3270 device available to a guest. Note that this supports basic |
| features only. |
| |
| To provide a 3270 device to a guest, create a ``x-terminal3270`` linked to |
| a ``tn3270`` chardev. The guest will see a 3270 channel device. In order |
| to actually be able to use it, attach the ``x3270`` emulator to the chardev. |
| |
| Example configuration |
| --------------------- |
| |
| * Make sure that 3270 support is enabled in the guest's Linux kernel. You need |
| ``CONFIG_TN3270`` and at least one of ``CONFIG_TN3270_TTY`` (for additional |
| ttys) or ``CONFIG_TN3270_CONSOLE`` (for a 3270 console). |
| |
| * Add a ``tn3270`` chardev and a ``x-terminal3270`` to the QEMU command line:: |
| |
| -chardev socket,id=ch0,host=0.0.0.0,port=2300,wait=off,server=on,tn3270=on |
| -device x-terminal3270,chardev=ch0,devno=fe.0.000a,id=terminal0 |
| |
| * Start the guest. In the guest, use ``chccwdev -e 0.0.000a`` to enable |
| the device. |
| |
| * On the host, start the ``x3270`` emulator:: |
| |
| x3270 <host>:2300 |
| |
| * In the guest, locate the 3270 device node under ``/dev/3270/`` (say, |
| ``tty1``) and start a getty on it:: |
| |
| systemctl start serial-getty@3270-tty1.service |
| |
| This should get you an additional tty for logging into the guest. |
| |
| * If you want to use the 3270 device as the Linux kernel console instead of |
| an additional tty, you can also append ``conmode=3270 condev=000a`` to |
| the guest's kernel command line. The kernel then should use the 3270 as |
| console after the next boot. |
| |
| Restrictions |
| ------------ |
| |
| 3270 support is very basic. In particular: |
| |
| * Only one 3270 device is supported. |
| |
| * It has only been tested with Linux guests and the x3270 emulator. |
| |
| * TLS/SSL is not supported. |
| |
| * Resizing on reattach is not supported. |
| |
| * Multiple commands in one inbound buffer (for example, when the reset key |
| is pressed while the network is slow) are not supported. |
