[systemd-devel] [PATCH 06/11] There is no ANSI support on common 3215 consoles

[Dr. Werner Fink]

On Fri, Jun 20, 2014 at 07:03:47PM +0200, Lennart Poettering wrote:
> 
> Also, we are not going to add code for any specific weird terminal
> settings. We will do three levels: TERM=linux for the full Linux
> console, TERM=vt102 otherwise, and TERM=dumb for the crap that can't do
> TERM=vt102. But we are not going to hardcode support for any other
> hardware into this. This is 2014. If IBM still can't build ANSI support in
> their terminals, then that's the own fault, and they will not get any
> support beyond TERM=dumb and no color. We will not work-around IBM's
> choices in systemd's source tree.
> 
> Sorry.

Maybe I'm wrong but this looks like you have no idea how S390x works.
The terminal emulation is done by the linux kernel which uses the
capabilities of the two block oriented terminal interfaces of the
firmware of a s390 (https://en.wikipedia.org/wiki/IBM_3270). One of
the block oriented terminals are able to do coloring (3270) and the
other (3215) is not.  Writing Escape Sequences (including carriage return)
will cause very strange effects with the later block oriented terminal
(3215) and this is the default interface if you to not use

   conmode=3270

to switch to 3270 mode.  With 3270 the kernel then maps Escape Sequences
with the help of linux/drivers/s390/char/tty3270.c onto the real firmware
interface for the chosen block oriented terminal.

I do not think that IBM will ``fix'' their s390 firmware due systemd.
Beside this, what happens if the main system console is a printer
and not a virtual device.  Or what does happen if it is a serial
console which can not handle Escape Sequences or can not handle all
Escape Sequences or use other Escape Sequences as a common VT102?

Werner

-- 
  "Having a smoking section in a restaurant is like having
          a peeing section in a swimming pool." -- Edward Burr
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