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

[Lennart Poettering]

On Fri, 01.08.14 16:07, Dr. Werner Fink (werner at suse.de) wrote:

> 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?

That's all good and fine. But we are not going to add explicit support
for this exotic stuff in systemd.

For cases like this we should support TERM=dumb. People won't get color
during boot, but things will still work great otherwise.

Lennart

-- 
Lennart Poettering, Red Hat