Re: [PATCH v5 2/2] target/xtensa: Use semihosting/syscalls.h

[Max Filippov]

On Wed, Jun 29, 2022 at 1:09 AM Alex Bennée <alex.bennee@linaro.org> wrote:
> Richard Henderson <richard.henderson@linaro.org> writes:
> > On 6/28/22 19:08, Max Filippov wrote:
> >> On Tue, Jun 28, 2022 at 4:43 AM Richard Henderson
> >> <richard.henderson@linaro.org> wrote:

> >>>       }
> >>> -    if (serial_hd(0)) {
> >>> -        xtensa_sim_open_console(serial_hd(0));
> >>> -    }
> >> I've noticed that with this change '-serial stdio' and its variants
> >> are still
> >> accepted in the command line, but now they do nothing.
> >
> > Pardon?  They certainly will do something, via writes to the serial 
> > hardware.
> >
> >
> >> This quiet
> >> change of behavior is unfortunate. I wonder if it would be acceptable
> >> to map the '-serial stdio' option in the presence of '-semihosting' to
> >> something like '-chardev stdio,id=id1 -semihosting-config chardev=id1'?
> >
> > I dunno.  I'm wary of having xtensa be unique here.  Alex, thoughts?
>
> Is semihosting *the* serial hardware for xtensa-sim or is it overriding
> another serial interface? I'm wary of adding more magical behaviour for
> -serial as it can be confusing enough already what actually gets routed
> to it if not doing everything explicitly.

There's no notion of 'serial hardware' for the xtensa-sim, all it has is
the three standard stdio file descriptors. But it was convenient thinking
of them as a serial port. I agree that no magic is needed here, but
the change shouldn't be quiet eiter, so xtensa-sim should warn (or
maybe even quit with an error code) when it sees the -serial option.

-- 
Thanks.
-- Max