bug#30505: Starting console/terminal Unicode support

[ludo@gnu.org (Ludovic Courtès)]

Hi,

Danny Milosavljevic <dannym@scratchpost.org> skribis:

> On Mon, 26 Feb 2018 18:09:53 +0100
> ludo@gnu.org (Ludovic Courtès) wrote:
>
>>   1. status quo, i.e., tcsetattr without %G in the ‘term-ttyN’ services;
>> 
>>   2. remove the tcsetattr call, write “1” to
>>      /sys/module/vt/parameters/default_utf8;
>> 
>>   3. do nothing (no tcsetattr, no /sys, no %G).
>> 
>> It seems that systemd does everything: %G, tcsetattr, and /sys.
>
> We have the following options as a distribution:
>
> (a) Hope that the user sets up everything as he should - iff they set up 
> the kernel as non-utf8, they also must set up an non-utf-8 console font.
> (b) Force their hand by decreeing that GuixSD is utf-8 only.  That's what
> we are doing now I think - and a lot of projects (GNOME etc) assume UTF-8
> nowadays anyway.
>
> Since we just want to fix the bug and leave everything else as it is (b),
> I'd vote for your (2.).
>
> (2.) needs to be done early before the VTs are actually there.

OK, makes sense, I agree.

> default_utf8 is a default, and it will be read only when defaulting, so
> in this case it will be read when Linux is constructing a tty.
>
> %base-services contain both console-font-service and mingetty-service which
> both access the ttys.  Linux VTs are created on demand.
>
> Once the VTs are created, us setting default_utf8 is too late.
>
> We should set default_utf8 before anyone touches tty[123456].
>
> Where will that be?
>
> Should we just set it in boot-system ? That's probably a nice way -
> also since I think this setting is quite Linux-specific.

Alternately we could introduce a ‘virtual-terminal’ service that every
‘term-*’ service would depend on.  That ‘virtual-terminal’ service would
simply write “1” to /sys/…/default_utf8.

How does that sound?

Ludo’.