Re: [PATCH] chardev: add nodelay option

[Paolo Bonzini]

On 02/03/21 12:33, Philippe Mathieu-Daudé wrote:
> On 3/2/21 12:04 PM, Paolo Bonzini wrote:
> > The "delay" option was introduced as a way to enable Nagle's algorithm
> > with ",nodelay".  Since the short form for boolean options has now been
> > deprecated, introduce a more properly named "nodelay" option.  The "delay"
> > option remains as an undocumented option.
> >
> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> > ---
> >   chardev/char-socket.c |  9 +++++++--
> >   gdbstub.c             |  2 +-
> >   qemu-options.hx       | 14 +++++++-------
> >   3 files changed, 15 insertions(+), 10 deletions(-)
> >
> > diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> > index 06a37c0cc8..73a7afe5a0 100644
> > --- a/chardev/char-socket.c
> > +++ b/chardev/char-socket.c
> > @@ -1472,8 +1472,13 @@ static void qemu_chr_parse_socket(QemuOpts *opts, 
> > ChardevBackend *backend,
> >       sock = backend->u.socket.data = g_new0(ChardevSocket, 1);
> >       qemu_chr_parse_common(opts, qapi_ChardevSocket_base(sock));
> >   
> > -    sock->has_nodelay = qemu_opt_get(opts, "delay");
> > -    sock->nodelay = !qemu_opt_get_bool(opts, "delay", true);
> > +    sock->has_nodelay =
> > +        qemu_opt_get(opts, "delay") ||
> > +        qemu_opt_get(opts, "nodelay");
> > +    sock->nodelay =
> > +        !qemu_opt_get_bool(opts, "delay", true) ||
> > +        qemu_opt_get_bool(opts, "nodelay", false);
>
> Should we add a deprecation note to remember to remove this later,
> or do we want to keep it infinitely? Then a comment here would be
> useful.

We cannot deprecate it only when options like -serial start warning for 
short-form boolean options (which I was going to propose for 6.1).  We 
probably also don't want a warning like "Please use delay=off instead"; 
suggesting "nodelay=on" would be an improvement (though an ugly one).

So the plan could be:

6.0: add "nodelay", deprecate -chardev short-form boolean options
6.1: deprecate "delay" and -serial short-form boolean options
6.2: some options (-M/-accel) start rejecting short-form boolean options
6.3: remove "delay"

Paolo