On 10/07/2020 12.55, Cornelia Huck wrote: > On Thu, 9 Jul 2020 18:04:39 +0200 > Thomas Huth <[email protected]> wrote: > >> There is some additional information about the 3270 support in our >> Wiki at https://wiki.qemu.org/Features/3270 - so let's include this >> information into the main documentation now to have one single >> source of information (the Wiki page could later be removed). > > No objection; but what should our general policy with regard to wiki > pages vs. documentation be? The 3270 support is pretty much static, but > e.g. for vfio-ccw, we use the wiki page as a place where we track > things that should be worked on etc.
I think that docs which are "done" should go into the git repo. If they are rather still work-in-progress and change very often, or relate to a feature that has not been merged yet, the wiki is likely the better place. > (Related: What is the scope of our QEMU documentation? Is a libvirt XML > snippet on topic? Kernel configuration options (as in here)?) As long as the focus is still on QEMU, I think it is fine. If the information is only about libvirt or the kernel, that documentation should maybe rather be added to libvirt.org or linux-kvm.org instead. >> Signed-off-by: Thomas Huth <[email protected]> >> --- >> docs/system/s390x/3270.rst | 43 ++++++++++++++++++++++++++++++++------ >> 1 file changed, 37 insertions(+), 6 deletions(-) >> >> diff --git a/docs/system/s390x/3270.rst b/docs/system/s390x/3270.rst >> index 1774cdcadf..80350264d7 100644 >> --- a/docs/system/s390x/3270.rst >> +++ b/docs/system/s390x/3270.rst >> @@ -1,9 +1,15 @@ >> 3270 devices >> ============ >> >> -QEMU supports connecting 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. >> +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 >> @@ -12,10 +18,14 @@ 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 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=char_0,host=0.0.0.0,port=2300,nowait,server,tn3270 >> - -device x-terminal3270,chardev=char_0,devno=fe.0.000a,id=terminal_0 >> + -chardev socket,id=ch0,host=0.0.0.0,port=2300,nowait,server,tn3270 >> + -device x-terminal3270,chardev=ch0,devno=fe.0.000a,id=terminal0 > > Any reason why you changed this? The lines were too long - Firefox displayed this example with a horizontal scrollbar, even if I resized the browser window large enough. With my change, it shows up nicely without scrollbar. >> >> * Start the guest. In the guest, use ``chccwdev -e 0.0.000a`` to enable >> the device. >> @@ -29,4 +39,25 @@ Example configuration >> >> systemctl start [email protected] >> >> -This should get you an addtional tty for logging into the guest. >> + This should get you an addtional tty for logging into the guest. >> + >> +* If you want to use the 3270 device as the 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 still experimental. In particular: > > s/still experimental/very basic/ > > I don't think there's much progress on the horizon; let's not give > people false hope :) > >> + >> +* Only one 3270 device is supported. >> + >> +* It has only been tested with Linux guests and the x3270 emulator. >> + >> +* TLS/SSL is not yet supported. > > s/yet // > >> + >> +* Resizing on reattach is not yet supported. > > s/yet // > >> + >> +* Multiple commands in one inbound buffer (for example, when the reset key >> + is pressed while the network is slow) are not yet supported. > > s/yet // > I'll fix these in v2. Thanks for the review! Thomas
