docs: Update preferred NBD device syntax

Mention the preferred URI form, especially since NBD is trying to
standardize that form: https://lists.debian.org/nbd/2019/06/msg00012.html

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190903145634.20237-1-eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>

diff --git a/qemu-doc.texi b/qemu-doc.texi
index 577d1e8376403037832eb1729fbf6108c7e373ba..ec460f1d7af558767359e9da0b8d4561516fe238 100644 (file)
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -297,9 +297,16 @@ qemu-system-i386 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
 
 @item NBD
 QEMU supports NBD (Network Block Devices) both using TCP protocol as well
-as Unix Domain Sockets.
+as Unix Domain Sockets.  With TCP, the default port is 10809.
 
-Syntax for specifying a NBD device using TCP
+Syntax for specifying a NBD device using TCP, in preferred URI form:
+``nbd://<server-ip>[:<port>]/[<export>]''
+
+Syntax for specifying a NBD device using Unix Domain Sockets; remember
+that '?' is a shell glob character and may need quoting:
+``nbd+unix:///[<export>]?socket=<domain-socket>''
+
+Older syntax that is also recognized:
 ``nbd:<server-ip>:<port>[:exportname=<export>]''
 
 Syntax for specifying a NBD device using Unix Domain Sockets