qemu-nbd: add support for --object command line arg

Allow creation of user creatable object types with qemu-nbd
via a new --object command line arg. This will be used to supply
passwords and/or encryption keys to the various block driver
backends via the recently added 'secret' object type.

 # printf letmein > mypasswd.txt
 # qemu-nbd --object secret,id=sec0,file=mypasswd.txt \
      ...other nbd args...

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1455129674-17255-3-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/qemu-nbd.texi b/qemu-nbd.texi
index 0027841ecb..a56ebc3433 100644
--- a/qemu-nbd.texi
+++ b/qemu-nbd.texi
@@ -18,6 +18,12 @@ Export a QEMU disk image using the NBD protocol.
 @var{dev} is an NBD device.
 
 @table @option
+@item --object type,id=@var{id},...props...
+Define a new instance of the @var{type} object class identified by @var{id}.
+See the @code{qemu(1)} manual page for full details of the properties
+supported. The common object type that it makes sense to define is the
+@code{secret} object, which is used to supply passwords and/or encryption
+keys.
 @item -p, --port=@var{port}
 The TCP port to listen on (default @samp{10809})
 @item -o, --offset=@var{offset}