Re: [PATCH] chardev/char-win-stdio: Support VT sequences on Windows 11 host

[Zhang Huasen]

From: Huasen Zhang <huasenzhang@foxmail.com>

Hello,

On Sat, 17 Jun 2023 11:42:06 +0200 Marc-André Lureau <
marcandre.lureau@redhat.com> wrote:
Hi

> On Fri, Jun 16, 2023 at 7:41 AM Zhang Huasen <huasenzhang@foxmail.com>
> wrote:
> 
> > From: Huasen Zhang <huasenzhang@foxmail.com>
> >
> > Hello,
> >
> > On Thu, 15 Jun 2023 12:57:55 +0200 Marc-André Lureau <
> > marcandre.lureau@redhat.com>
> > wrote:
> > > Hi
> > >
> > > On Thu, Jun 15, 2023 at 12:36 PM Zhang Huasen <huasenzhang@foxmail.com>
> > > wrote:
> > >
> > > > If the monitor or the serial port use STDIO as backend on Windows 11
> > > > host,
> > > > e.g. -nographic options is used, the monitor or the guest Linux do not
> > > > response to arrow keys.
> > > >
> > > > When Windows creates a console, ENABLE_VIRTUAL_PROCESS_INPUT is
> > > > disabled
> > > > by default. Arrow keys cannot be retrieved by ReadFile or
> > > > ReadConsoleInput
> > > > functions.
> > > >
> > > > Add ENABLE_VIRTUAL_PROCESS_INPUT to the flag which is passed to
> > > > SetConsoleMode,
> > > > when opening stdio console.
> > > >
> > > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1674
> > > >
> > > > Signed-off-by: Zhang Huasen <huasenzhang@foxmail.com>
> > > > ---
> > > >  chardev/char-win-stdio.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/chardev/char-win-stdio.c b/chardev/char-win-stdio.c
> > > > index eb830eabd9..1a18999e78 100644
> > > > --- a/chardev/char-win-stdio.c
> > > > +++ b/chardev/char-win-stdio.c
> > > > @@ -190,7 +190,7 @@ static void qemu_chr_open_stdio(Chardev *chr,
> > > >          }
> > > >      }
> > > >
> > > > -    dwMode |= ENABLE_LINE_INPUT;
> > > > +    dwMode |= ENABLE_LINE_INPUT | ENABLE_VIRTUAL_TERMINAL_INPUT;
> > > >
> > >
> > > I think we should set it only when is_console (although that may not
> > > make a
> > > difference otherwise)
> >
> > It is okay to set ENABLE_VIRTUAL_TERMINAL_INPUT only when is_console is
> > TRUE.
> >
> > I do not understand some points of original code.
> > If the stdin is not a console, i.e. GetConsoleMode fails, we still
> > call SetConsoleMode and set ENABLE_LINE_INPUT.
> > Could you please tell what the purpose is?
> >
> 
> I have no clue. It has been this way since the beginning (commit db418a0a7).
> 
> The code doesn't check SetConsoleMode() return value, so I'd just go with
> your patch for now.
Thanks for your review and comments.