Re: [PATCH] chardev: add nodelay option

[Paolo Bonzini <pbonzini@redhat.com>]

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