bug#30505: Starting console/terminal Unicode support

[Danny Milosavljevic <dannym@scratchpost.org>]

Hi Ludo,

On Wed, 21 Feb 2018 23:21:34 +0100
ludo@gnu.org (Ludovic Courtès) wrote:

> >> This ‘unicode-start’ procedure is essentially a port of the
> >> ‘unicode_start’ script from ‘kbd’.  I suppose the justification is to
> >> make sure we’re using UTF-8 input regardless of what the kernel defaults
> >> or command-line options are.  

Yeah, but the only way to have it not use utf-8 would be to explicitly pass
"default_utf8=0" as a command-line parameter.  I think at that point the
user deserves what he personally asked for :P

>In
> other cases (custom kernel build with different defaults, different
> kernel command-line settings, etc.), we’d just get it wrong with things
> breaking down the path, no?

Yes, it would just default to ASCII.  In the big scheme of things it's not so bad.

I just thought that if it causes trouble *and* it's not needed anymore, the
simplest way is to just remove it.

> Also, FWIW, systemd’s vconsole-setup.c does exactly that:
> 
>   https://github.com/systemd/systemd/blob/master/src/vconsole/vconsole-setup.c#L94

Huh, I wonder why they do it.  systemd is quite new.  I understand that older stuff
(like kbd) did it because they had to in the Linux 2.4 days - but this?

We should ask them...

Aha, they also have

static int toggle_utf8_sysfs(bool utf8) {
        int r;

        r = write_string_file("/sys/module/vt/parameters/default_utf8", one_zero(utf8), 0);
        if (r < 0)
                return log_warning_errno(r, "Failed to %s sysfs UTF-8 flag: %m", enable_disable(utf8));

        log_debug("Sysfs UTF-8 flag %sd", enable_disable(utf8));
        return 0;
}

so we could in fact directly force the VT driver to do our bidding, or even
check what's up before trying to write the 'G' (the latter sounds like a hack
hiding the actual problem, though).