b5408666f1
The virtio-gpio driver at the guest performs virtio transaction right from its probe() routine and without this patch, there is a chance that the backend may miss the notification from the guest, as the notification may be sent before the eventfd is set at the backend. This flag makes the master side wait for reply from backend before proceeding further for each operation. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> |
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| src | ||
| Cargo.toml | ||
| README.md | ||
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: [:]
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 "0" path.
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
...