audio: Add sndio backend

sndio is the native API used by OpenBSD, although it has been ported to
other *BSD's and Linux (packages for Ubuntu, Debian, Void, Arch, etc.).

Signed-off-by: Brad Smith <brad@comstyle.com>
Signed-off-by: Alexandre Ratchov <alex@caoua.org>
Reviewed-by: Volker RĂ¼melin <vr_qemu@t-online.de>
Tested-by: Volker RĂ¼melin <vr_qemu@t-online.de>
Message-Id: <YxibXrWsrS3XYQM3@vm1.arverb.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index d8b5ce5..2ff0688 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -769,6 +769,9 @@
     "-audiodev sdl,id=id[,prop[=value][,...]]\n"
     "                in|out.buffer-count= number of buffers\n"
 #endif
+#ifdef CONFIG_AUDIO_SNDIO
+    "-audiodev sndio,id=id[,prop[=value][,...]]\n"
+#endif
 #ifdef CONFIG_SPICE
     "-audiodev spice,id=id[,prop[=value][,...]]\n"
 #endif
@@ -935,6 +938,19 @@
     ``in|out.buffer-count=count``
         Sets the count of the buffers.
 
+``-audiodev sndio,id=id[,prop[=value][,...]]``
+    Creates a backend using SNDIO. This backend is available on
+    OpenBSD and most other Unix-like systems.
+
+    Sndio specific options are:
+
+    ``in|out.dev=device``
+        Specify the sndio device to use for input and/or output. Default
+        is ``default``.
+
+    ``in|out.latency=usecs``
+        Sets the desired period length in microseconds.
+
 ``-audiodev spice,id=id[,prop[=value][,...]]``
     Creates a backend that sends audio through SPICE. This backend
     requires ``-spice`` and automatically selected in that case, so