The dfirst thing is to make use of _Configuration Fragments_. These are files ending in `.cfg` that contain fragments of configuration for things like the Kernel. The configuration fragment will be applied to the configuration _after_ the main `.config` file has been applied.
e.g. to enable USB Cameras, you can create a `cameras.cfg` file containing:
“`
CONFIG_MEDIA_CAMERA_SUPPORT=y
CONFIG_VIDEO_V4L2_SUBDEV_API=y
ONFIG_V4L2_FWNODE=y
CONFIG_V4L2_ASYNC=y
CONFIG_MEDIA_USB_SUPPORT=y
CONFIG_USB_VIDEO_CLASS=y
CONFIG_USB_VIDEO_CLASS_INPUT_EVDEV=y
“`

Then, you will need an append file in **your** layer, e.g. `layers/project/meta-my_bsp/recipes-kernel/linux-yocto/linux-yocto_%.bbappend` containing
“`
FILESEXTRAPATHS:prepend := “${THISDIR}/${PN}:”

SRC_URI:append= ” file://cameras.cfg”
“`

Then put the `cameras.cfg` in `layers/project/meta-my_bsp/recipes-kernel/linux-yocto/linux-yocto/cameras.cfg`

This will get applied to _all_ machines.

If you now have two machines defined, say, `my-eye` that has a camera and `my-blind` , then to configure it so that only `my-eye` picks up the camera configuration, you can change the append file to make use of `conditional overrides`.

This makes use of the OVERRIDES variable, which by default contains the Architecture, the OS and the Machine name.
The format of an override is
`VARIABLE:append:override`

So, to only have `my-eye` pick up the camera configuration, the value of `SRC_URI` needs to be
`SRC_URI:append:my-eye = ” file://cameras.cfg”`

This way the `camera.cfg` would **only** get picked up if the machine `my-eye` is used.