From: Mathieu Poirier <mathieu.poir...@linaro.org>
Add description and example for the vhost-user based RNG implementation.
Tailored on Viresh Kumar's vhost-user-i2c documentation.
Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
Message-Id: <20210710005929.1702431-5-mathieu.poir...@linaro.org>
Reviewed-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
docs/tools/index.rst | 1 +
docs/tools/vhost-user-rng.rst | 74 +++++++++++++++++++++++++++++++++++
2 files changed, 75 insertions(+)
create mode 100644 docs/tools/vhost-user-rng.rst
diff --git a/docs/tools/index.rst b/docs/tools/index.rst
index d923834a73..9d80fa89ec 100644
--- a/docs/tools/index.rst
+++ b/docs/tools/index.rst
@@ -15,5 +15,6 @@ Contents:
qemu-nbd
qemu-pr-helper
qemu-trace-stap
+ vhost-user-rng
virtfs-proxy-helper
virtiofsd
diff --git a/docs/tools/vhost-user-rng.rst b/docs/tools/vhost-user-rng.rst
new file mode 100644
index 0000000000..7f69d7bb3c
--- /dev/null
+++ b/docs/tools/vhost-user-rng.rst
@@ -0,0 +1,74 @@
+QEMU vhost-user-rng - RNG emulation backend
+===========================================
+
+Synopsis
+--------
+
+**vhost-user-rng** [*OPTIONS*]
+
+Description
+-----------
+
+This program is a vhost-user backend that emulates a VirtIO random number
+generator (RNG). It uses the host's random number generator pool,
+/dev/urandom by default but configurable at will, to satisfy requests from
+guests.
+
+This program is designed to work with QEMU's ``-device
+vhost-user-rng-pci`` but should work with any virtual machine monitor
+(VMM) that supports vhost-user. See the Examples section below.
+
+Options
+-------
+
+.. program:: vhost-user-rng
+
+.. option:: -h, --help
+
+ Print help.
+
+.. option:: -v, --verbose
+
+ Increase verbosity of output
+
+.. option:: -s, --socket-path=PATH
+
+ Listen on vhost-user UNIX domain socket at PATH. Incompatible with --fd.
+
+.. option:: -f, --fd=FDNUM
+
+ Accept connections from vhost-user UNIX domain socket file descriptor FDNUM.
+ The file descriptor must already be listening for connections.
+ Incompatible with --socket-path.
+
+.. option:: -p, --period
+
+ Rate, in milliseconds, at which the RNG hardware can generate random data.
+ Used in conjunction with the --max-bytes option.
+
+.. option:: -m, --max-bytes
+
+ In conjuction with the --period parameter, provides the maximum number of
byte
+ per milliseconds a RNG device can generate.
+
+Examples
+--------
+
+The daemon should be started first:
+
+::
+
+ host# vhost-user-rng --socket-path=rng.sock --period=1000 --max-bytes=4096
+
+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
\
+ ...
--
MST
