Re: [PATCH] virtio-gpio: Specify character encoding for gpio names

[Arnd Bergmann <arnd@kernel.org>]

On Wed, Aug 18, 2021 at 1:31 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> diff --git a/virtio-gpio.tex b/virtio-gpio.tex
> index 5da16d920aa3..0b0689cceb08 100644
> --- a/virtio-gpio.tex
> +++ b/virtio-gpio.tex
> @@ -119,7 +119,8 @@ \subsubsection{requestq Operation: Get Line Names}\label{sec:Device Types / GPIO
>  order of the GPIO line numbers. The names of the GPIO lines are optional and may
>  be present only for a subset of GPIO lines. If missing, then a zero-byte must be
>  present for the GPIO line. If present, the name string must be zero-terminated
> -and the name must be unique within a GPIO Device.
> +and the name must be unique within a GPIO Device. The names of the GPIO lines
> +are encoded in UTF-8.

I would prefer mandating this to be 7-bit ASCII, since Linux uses the string as
a file name in the (deprecated) sysfs interface, and the more unusual symbols
may be hard to type on the command line.

There is also a question about UTF-8 normalization of those strings: should
the guest assume that the names within a device just have different binary
representations, or also that they represent unique strings when there are
multiple equivalent or compatible sequences?

       Arnd