vhost-device/vhost-device-gpio/README.md
Manos Pitsidianakis a1e013286f Move all crates to workspace root
Having all the workspace crates under the crates/ directory is
unnecessary. Rust documentation itself recommends all crates to be in
the root directory:

https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html#creating-the-second-package-in-the-workspace

I paste the text content here, in case the online page ever changes or
becomes unavailable:

    ## Creating the Second Package in the Workspace

    Next, let’s create another member package in the workspace and call it add_one. Change the top-level Cargo.toml to specify the add_one path in the members list:

    Filename: Cargo.toml

    [workspace]

    members = [
        "adder",
        "add_one",
    ]

    Then generate a new library crate named add_one:

    $ cargo new add_one --lib
         Created library `add_one` package

    Your add directory should now have these directories and files:

    ├── Cargo.lock
    ├── Cargo.toml
    ├── add_one
    │   ├── Cargo.toml
    │   └── src
    │       └── lib.rs
    ├── adder
    │   ├── Cargo.toml
    │   └── src
    │       └── main.rs
    └── target

Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
2023-10-16 12:03:57 +05:30

95 lines
3.0 KiB
Markdown

# vhost-device-gpio - GPIO emulation backend daemon
## Description
This program is a vhost-user backend that emulates a VirtIO GPIO device. This
program takes a list of gpio devices on the host OS and then talks to them via
the /dev/gpiochip{X} interface when a request comes from the guest OS for an
GPIO device.
This program is tested with QEMU's `-device vhost-user-gpio-pci` but should
work with any virtual machine monitor (VMM) that supports vhost-user. See the
Examples section below.
## Synopsis
**vhost-device-gpio** [*OPTIONS*]
## Options
.. program:: vhost-device-gpio
.. option:: -h, --help
Print help.
.. option:: -s, --socket-path=PATH
Location of vhost-user Unix domain sockets, this path will be suffixed with
0,1,2..socket_count-1.
.. option:: -c, --socket-count=INT
Number of guests (sockets) to attach to, default set to 1.
.. option:: -l, --device-list=GPIO-DEVICES
GPIO device list at the host OS in the format:
<device1>[:<device2>]
Example: --device-list "2:4:7"
Here, each GPIO devices correspond to a separate guest instance, i.e. the
number of devices in the device-list must match the number of sockets in the
--socket-count. For example, the GPIO device 0 will be allocated to the guest
with "<socket-path>0" path.
## MockGpioDevice support
As connecting VM guests to random GPIO pins on your host is generally
asking for trouble you can enable the "mock_gpio" feature in your build:
cargo build --features "mock_gpio"
You can then enable simulated GPIOs using the 's' prefix:
--device-list s4,s8
Which will create two gpio devices, the first with 4 pins and the
second with 8. By default updates are display via env logger:
vhost-device-gpio -s /tmp/vus.sock -c 1 -l s4
[2023-09-14T14:15:14Z INFO vhost_device_gpio::mock_gpio] gpio dummy0 set value to 1
[2023-09-14T14:15:14Z INFO vhost_device_gpio::mock_gpio] gpio dummy0 set direction to 1
[2023-09-14T14:15:14Z INFO vhost_device_gpio::mock_gpio] gpio dummy0 set direction to 0
[2023-09-14T14:15:19Z INFO vhost_device_gpio::mock_gpio] gpio dummy1 set value to 1
[2023-09-14T14:15:19Z INFO vhost_device_gpio::mock_gpio] gpio dummy1 set direction to 1
[2023-09-14T14:15:19Z INFO vhost_device_gpio::mock_gpio] gpio dummy1 set direction to 0
## Examples
The daemon should be started first:
::
host# vhost-device-gpio --socket-path=gpio.sock --socket-count=1 --device-list 0:3
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=vgpio.sock,id=vgpio \
-device vhost-user-gpio-pci,chardev=vgpio,id=gpio \
-m 4096 \
-object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on \
-numa node,memdev=mem \
...
## License
This project is licensed under either of
- [Apache License](http://www.apache.org/licenses/LICENSE-2.0), Version 2.0
- [BSD-3-Clause License](https://opensource.org/licenses/BSD-3-Clause)