docs/system: drop vhost-user-rng docs

This is a fairly lightweight document which doesn't add much to the
general advice in vhost-user. Update the vhost-user docs to point
directly at the rust-vmm repo.

Reviewed-by: John Levon <john.levon@nutanix.com>
Message-ID: <20251016150357.876415-11-alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

docs/system/devices/virtio/index.rst

@@ -25,6 +25,5 @@ can also be off-loaded to an external process via :ref:`vhost user
    virtio-snd.rst
    vhost-user.rst
    vhost-user-input.rst
-   vhost-user-rng.rst
 
 .. _VirtIO specification: https://docs.oasis-open.org/virtio/virtio/v1.3/virtio-v1.3.html

docs/system/devices/virtio/vhost-user-rng.rst

@@ -1,41 +0,0 @@
-.. _vhost_user_rng:
-
-QEMU vhost-user-rng - RNG emulation
-===================================
-
-Background
-----------
-
-What follows builds on the material presented in vhost-user.rst - it should
-be reviewed before moving forward with the content in this file.
-
-Description
------------
-
-The vhost-user-rng device implementation was designed to work with a random
-number generator daemon such as the one found in the vhost-device crate of
-the rust-vmm project available on github [1].
-
-[1]. https://github.com/rust-vmm/vhost-device
-
-Examples
---------
-
-The daemon should be started first:
-
-::
-
-  host# vhost-device-rng --socket-path=rng.sock -c 1 -m 512 -p 1000
-
-The QEMU invocation needs to create a chardev socket the device can
-use to communicate as well as share the guests memory over a memfd.
-
-::
-
-  host# qemu-system								\
-      -chardev socket,path=$(PATH)/rng.sock,id=rng0				\
-      -device vhost-user-rng-pci,chardev=rng0					\
-      -m 4096 									\
-      -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on	\
-      -numa node,memdev=mem							\
-      ...

docs/system/devices/virtio/vhost-user.rst

@@ -45,7 +45,7 @@ platform details for what sort of virtio bus to use.
     - :ref:`vhost_user_input`
   * - vhost-user-rng
     - Entropy driver
-    - :ref:`vhost_user_rng`
+    - See https://github.com/rust-vmm/vhost-device
   * - vhost-user-scmi
     - System Control and Management Interface
     - See https://github.com/rust-vmm/vhost-device