On 11 Jul 2020, at 20:31, Daan De Meyer <daan.j.demeyer@xxxxxxxxx> wrote:
> TERM=linux means Linux console, but that's just too much, as it not > only implies a multitude of ESC sequences specific to the Linux > console, but also indicates that certain ioctls might work. In our own > code we also bind certain behaviour to TERM=linux, as indicator if we > are on the Linux console.
> > I am not aware of any widely-supported TERM value that would be a > reasonable subset of all currently used terminals and does color.
I did some more research and it turns out VT220 does support colors. My terminal emulator (Konsole) just doesn't seem to support it. I installed xterm (which explicitly advertises support for VT220 escape codes) and got colored output as expected. I guess this means it's up to Konsole to support more of VT220 if I want this to work seamlessly (or I switch terminals to xterm).
No vt220 does not support colour. I used to work on one and it is monochrome hardware. Xterm and konsole support extensions beyond vt220 that add in the colour support.
Barry
Thanks for the extra info and context.
Daan
On Sa, 11.07.20 17:51, Daan De Meyer (daan.j.demeyer@xxxxxxxxx) wrote:
> Hi,
>
> I was playing around with mkosi's qemu support, more specifically adding
> the -nographic option to have the virtual machine output in my terminal
> instead of a separate window. After figuring out that I had to add
> console=ttyS0 to mkosi's kernel command line, I got the output from the vm
> in my terminal as expected. However, because systemd defaults to TERM=vt220
> for serial consoles, the output is not colorized. I searched around a bit
> and found that this is done for compatibility reasons. Will there ever be a
> point where we can switch the default to something that supports colors
> (like TERM=linux)?
TERM=linux means Linux console, but that's just too much, as it not
only implies a multitude of ESC sequences specific to the Linux
console, but also indicates that certain ioctls might work. In our own
code we also bind certain behaviour to TERM=linux, as indicator if we
are on the Linux console.
I am not aware of any widely-supported TERM value that would be a
reasonable subset of all currently used terminals and does color.
> I managed to get around the problem by overriding serial-getty@ttyS0 and
> setting Environment=TERM=linux explicitly but it's a bit of a pain and has
> to be added to every rootfs that wants to support colored output on its
> serial console.
Unfortunately we can't guess the right terminal, we cannot propagate
TERM=xterm or TERM=linux depending if you invoke qemu on an xterm or
from a Linux console, hence the best thing we can do is stick to a
reasonably powerful subset that is likely going to exist everywhere,
and that's vt220 right now, as noone had a better suggestion so far...
Lennart
--
Lennart Poettering, Berlin
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