|0.1.0||Sep 5, 2023|
#364 in Hardware support
This program is a vhost-user backend for a VirtIO SCMI device. It provides SCMI access to various entities on the host; not necessarily only those providing an SCMI interface themselves.
It is tested with QEMU's
-device vhost-user-scmi-pci but should work
with any virtual machine monitor (VMM) that supports vhost-user. See
the Examples section below.
.. program:: vhost-device-scmi
.. option:: -h, --help
.. option:: -s, --socket-path=PATH
Location of the vhost-user Unix domain sockets.
.. option:: -d, --device=SPEC
SCMI device specification in the format
Can be used multiple times for multiple exposed devices. If no device is specified then no device will be provided to the guest OS but VirtIO SCMI will be still available there. Use
--help-devices to list help on all the available devices.
You can set
RUST_LOG environment variable to
debug to get maximum
messages on the standard error output.
The daemon should be started first:
host# vhost-device-scmi --socket-path=scmi.sock --device fake,name=foo
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:
Supported SCMI protocols
The currently supported SCMI protocols are:
- sensor management
Basically only the mandatory and necessary parts of the protocols are implemented.
See source code (
scmi crate) documentation for details and how to
add more protocols, host device bindings or other functionality.
SCMI is supported only on Arm in Linux. This restriction doesn't apply to the host, which can be any architecture as long as the guest is Arm.
The easiest way to test it on the guest side is using the Linux SCMI
Industrial I/O driver there. If an 3-axes accelerometer or gyroscope
VirtIO SCMI device is present and the guest kernel is compiled with
CONFIG_IIO_SCMI enabled then the device should be available in
/sys/bus/iio/devices/. The vhost-device-scmi fake device is
suitable for this.
Of course, other means of accessing SCMI devices can be used too. The
following Linux kernel command line can be useful to obtain SCMI trace
information, in addition to SCMI related messages in dmesg:
trace_event=scmi:* ftrace=function ftrace_filter=scmi*.
Kernel support for testing
kernel subdirectory contains
instructions how to create emulated
industrial I/O devices for testing.
This project is licensed under either of
unless specified in particular files otherwise.