Varlink kernel protocol driver module.
$ modinfo drivers/varlink/varlink.ko
filename: /src/varlink/linux-varlink/drivers/varlink/varlink.ko
description: Varlink Protocol Driver
license: GPL
depends:
name: varlink
vermagic: 4.13.10-200.fc26.x86_64 SMP mod_unload
Example driver using the varlink module. It creates a device node at /dev/org.kernel.example and offers two interfaces.
$ modinfo drivers/example/example.ko
filename: /src/varlink/linux-varlink/drivers/example/example.ko
description: Varlink Example
license: GPL
depends: varlink
name: example
vermagic: 4.13.10-200.fc26.x86_64 SMP mod_unload
Information about the example kernel driver module.
$ varlink info device:/dev/org.kernel.example
Vendor: Linux
Product: Varlink Example
Version: 1.0
URL: http://kernel.org
Interfaces:
org.kernel.devices.usb
org.kernel.sysinfo
Interface with uname information.
$ varlink call device:/dev/org.kernel.example/org.kernel.sysinfo.GetInfo
{
"domainname": "(none)",
"machine": "x86_64",
"nodename": "ank",
"release": "4.13.10-200.fc26.x86_64",
"sysname": "Linux",
"version": "#1 SMP Fri Oct 27 15:34:40 UTC 2017"
}Interface to enumerate and monitor USB devices, --more subscribes to changes. The log below shows events for the mouse removed and added back.
$ varlink call --more device:/dev/org.kernel.example/org.kernel.devices.usb.Monitor
{
"devices": [
{
"bus_nr": 1,
"device_nr": 1,
"manufacturer": "Linux 4.13.10-200.fc26.x86_64 xhci-hcd",
"product": "xHCI Host Controller",
"product_id": 2,
"serial": "0000:00:14.0",
"vendor_id": 7531
},
{
"bus_nr": 2,
"device_nr": 1,
"manufacturer": "Linux 4.13.10-200.fc26.x86_64 xhci-hcd",
"product": "xHCI Host Controller",
"product_id": 3,
"serial": "0000:00:14.0",
"vendor_id": 7531
},
{
"bus_nr": 1,
"device_nr": 3,
"manufacturer": "Yubico",
"product": "Yubico Yubikey II",
"product_id": 16,
"serial": "0002883373",
"vendor_id": 4176
},
{
"bus_nr": 1,
"device_nr": 5,
"manufacturer": "Chicony Electronics Co.,Ltd.",
"product": "Integrated Camera",
"product_id": 46385,
"serial": "0001",
"vendor_id": 1266
},
{
"bus_nr": 1,
"device_nr": 6,
"manufacturer": "",
"product": "",
"product_id": 144,
"serial": "00ea88d95461",
"vendor_id": 5002
},
{
"bus_nr": 1,
"device_nr": 7,
"manufacturer": "Logitech",
"product": "USB Laser Mouse",
"product_id": 49257,
"serial": "",
"vendor_id": 1133
}
],
"event": "current"
}
{
"devices": [
{
"bus_nr": 1,
"device_nr": 7,
"manufacturer": "Logitech",
"product": "USB Laser Mouse",
"product_id": 49257,
"serial": "",
"vendor_id": 1133
}
],
"event": "remove"
}
{
"devices": [
{
"bus_nr": 1,
"device_nr": 8,
"manufacturer": "Logitech",
"product": "USB Laser Mouse",
"product_id": 49257,
"serial": "",
"vendor_id": 1133
}
],
"event": "add"
}Simple read/write operations on the device nodes, exchanging JSON.
$ strace -s 1000 varlink call device:/dev/org.kernel.example/org.kernel.sysinfo.GetInfo
[...]
open("/dev/org.kernel.example", O_RDWR|O_CLOEXEC) = 5
write(5, "{\"method\":\"org.kernel.sysinfo.GetInfo\"}\0", 40) = 0
read(5, "{\"parameters\":{\"domainname\":\"(none)\",\"machine\":\"x86_64\",\"nodename\":\"ank\",\"release\":\"4.13.10-200.fc26.x86_64\",\"sysname\":\"Linux\",\"version\":\"#1 SMP Fri Oct 27 15:34:40 UTC 2017\"}}\0", 16777216) = 177
[...]