monitor: new parameter "x-oob"

Add new parameter to optionally enable Out-Of-Band for a QMP server.

An example command line:

  ./qemu-system-x86_64 -chardev stdio,id=char0 \
                       -mon chardev=char0,mode=control,x-oob=on

By default, Out-Of-Band is off.

It is not allowed if either MUX or non-QMP is detected, since
Out-Of-Band is currently only for QMP, and non-MUX chardev backends.

Note that the client STILL has to request 'oob' during qmp_capabilities;
in part because the x-oob command line option may disappear in the
future if we decide the capabilities negotiation is sufficient.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180326063901.27425-4-peterx@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
[eblake: enhance commit message]
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/vl.c b/vl.c
index c81cc86..5fd01bd 100644
--- a/vl.c
+++ b/vl.c
@@ -2404,6 +2404,11 @@ static int mon_init_func(void *opaque, QemuOpts *opts, Error **errp)
     if (qemu_opt_get_bool(opts, "pretty", 0))
         flags |= MONITOR_USE_PRETTY;
 
+    /* OOB is off by default */
+    if (qemu_opt_get_bool(opts, "x-oob", 0)) {
+        flags |= MONITOR_USE_OOB;
+    }
+
     chardev = qemu_opt_get(opts, "chardev");
     chr = qemu_chr_find(chardev);
     if (chr == NULL) {