4.25.2. Using devtmpfs and a Device Manager

To use the dynamic method for device population, you need to use (or be sure to set) the USE_DEVFS variable to "1", which is the default:

     USE_DEVFS = "1"
                

With this setting, the resulting /dev directory is populated by the kernel using devtmpfs. Make sure the corresponding kernel configuration variable CONFIG_DEVTMPFS is set when building you build a Linux kernel.

All devices created by devtmpfs will be owned by root and have permissions 0600.

To have more control over the device nodes, you can use a device manager like udev or busybox-mdev. You choose the device manager by defining the VIRTUAL-RUNTIME_dev_manager variable in your machine or distro configuration file. Alternatively, you can set this variable in your local.conf configuration file:

     VIRTUAL-RUNTIME_dev_manager = "udev"

     # Some alternative values
     # VIRTUAL-RUNTIME_dev_manager = "busybox-mdev"
     # VIRTUAL-RUNTIME_dev_manager = "systemd"