linux-kernel - Re: [PATCH 00/53] Get rid of UTF-8 chars that can be mapped as ASCII

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Date:   Mon, 10 May 2021 23:57:13 +0200
From:   Adam Borowski <kilobyte@...band.pl>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc:     Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        linux-kernel@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        alsa-devel@...a-project.org, coresight@...ts.linaro.org,
        dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        intel-wired-lan@...ts.osuosl.org, keyrings@...r.kernel.org,
        kvm@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-edac@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-fpga@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-input@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-media@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-rdma@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-sgx@...r.kernel.org, linux-usb@...r.kernel.org,
        mjpeg-users@...ts.sourceforge.net, netdev@...r.kernel.org,
        rcu@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 00/53] Get rid of UTF-8 chars that can be mapped as ASCII

On Mon, May 10, 2021 at 12:26:12PM +0200, Mauro Carvalho Chehab wrote:
> There are several UTF-8 characters at the Kernel's documentation.
[...]
> Other UTF-8 characters were added along the time, but they're easily
> replaceable by ASCII chars.
> 
> As Linux developers are all around the globe, and not everybody has UTF-8
> as their default charset

I'm not aware of a distribution that still allows selecting a non-UTF-8
charset in a normal flow in their installer.  And if they haven't purged
support for ancient encodings, that support is thoroughly bitrotten.
Thus, I disagree that this is a legitimate concern.

What _could_ be a legitimate reason is that someone is on a _terminal_
that can't display a wide enough set of glyphs.  Such terminals are:
 • Linux console (because of vgacon limitations; patchsets to improve
   other cons haven't been mainlined)
 • some Windows terminals (putty, old Windows console) that can't borrow
   glyphs from other fonts like fontconfig can

For the former, it's whatever your distribution ships in
/usr/share/consolefonts/ or an equivalent, which is based on historic
ISO-8859 and VT100 traditions.

For the latter, the near-guaranteed character set is WGL4.

Thus, at least two of your choices seem to disagree with the above:
[dropped]
> 	0xd7   => 'x',		# MULTIPLICATION SIGN
[retained]
> 	- U+2b0d ('⬍'): UP DOWN BLACK ARROW

× is present in ISO-8859, V100, WGL4; I've found no font in
/usr/share/consolefonts/ on my Debian unstable box that lacks this
character.

⬍ is not found in any of the above.  You might want to at least
convert it to ↕ which is at least present in WGL4, and thus likely
to be supported in fonts heeding Windows/Mac/OpenType recommendations.
That still won't make it work on VT.

Meow!
-- 
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