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These variants are referred to as "platforms". Different variants of EVE are built by calling:

make eve PLATFORM=<platform>

With some of these variants, we need not only specific kernels, but also specific files to be available on the system. These cannot be downloaded runtime because:

• The data source with the packages might not be available to end devices at boot time;
• Even if the data source is available, it might be bandwidth constrained;
• The device might need the files very soon after startup.

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All device-specific files should be placed on the root filesystem in:

 /opt/vendor/<vendorname>/

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Note that, by definition, no 2 platforms platform-specific versions of EVE are the same and built for the same platform. Thus, it is highly likely that in all cases there will be either zero (no device-specific flavour) or one (device-specific flavour) subdirectory under /opt/vendor/ . ThusFor example, an Nvidia Jetson EVE will have /opt/vendor/nvidia , while an imx EVE will have /opt/vendor/imx . In theory, we could simply place everything under /opt/vendor  and avoid another layer of device-name-specific subdirectory. We choose not to do this for two reasons.

1. We cannot guarantee that in the future we never will have a device with files from two distinct vendors; the /opt/vendor/<vendor_name>  structure  structure provides future flexibility.
2. We make analysis Analysis and debugging are much easier if it explicitly states what the device the vendor-specific files are for.

The directory /opt/vendor/  will can be available mounted to any system container that needs it as a mount in rootfs.yml . In addition, it It always will be mounted into pillar as /opt/vendor:/opt/vendor  into pillar as a standard.

Populating Vendor Directory

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Any device that requires a Board Support Package (BSP) should create a container via a directory in lf-edge/eve/pkg/bsp-<vendor> , e.g. bsp-imx  (which already exists) or bsp-nvidia . The contents of the final stage in the Dockerfile must be FROM scratch  and must save files solely to /opt/vendor/<vendorname>  so that the files will be properly placed in the rootfs.

The actual update of rootfs.yml  on a per-vendor basis, so that the files can be placed in the base operating system, is covered in the later section "Device-Specific Files".

Long-Running Services

If the device requires device-specific long-running services, for example a fan or other device controller, these are considered system-level services, and should be added to the services  section of rootfs.yml .

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It should avoid duplicating any files already in /opt/vendor/<vendor> , instead mounting those in, if at all possible.

The actual update of rootfs.yml  on a per-vendor basis, so that the the services  section can be modified, is covered in the later section "Device-Specific Files".

Startup Services

If the device requires startup services, it depends upon the nature of the startup service:

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It should avoid duplicating any files already in /opt/vendor/<vendor> , instead mounting those in, if at all possible.

The actual update of rootfs.yml  on a per-vendor basis, so that the files can be placed in the onboot  section, is covered in the later section "Device-Specific Files".

Pillar-Specific

Pillar-specific startup services, e.g. modifications to user containerd config.toml  or communications, should be performed by pillar itself.

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The only permanent change is to always have /opt/vendor:/opt/vendor  mounted into pillar. This is done by modifying actually does not require changing rootfs.yml , but instead extending permissions in the pillar image. We modify pkg/pillar/build.yml:

org: lfedge
image: eve-pillar
config:
  binds:
    - /lib/modules:/lib/modules
    - /dev:/dev
    - /etc/resolv.conf:/etc/resolv.conf
    - /run:/run
    - /config:/config
    - /:/hostfs
    - /persist:/persist:rshared,rbind
    - /usr/bin/containerd:/usr/bin/containerd
    - /opt/vendor:/opt/vendor     # <---- NEW
  net: host
  capabilities:
    - all
  pid: host
  rootfsPropagation: shared
  devices:
    - path: all
      type: a

Dynamic

Dynamic changes to rootfs.yml  are ones that sometimes are added and sometimes are not. Before we describe the mechanism, we need to describe how yml generation currently works, and changes to extend it.

Extending and Standardizing yml generation

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Modifier for Specific Device Files

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With the above generic extension mechanism in place, we can update rootfs.yml  for specific device files by:

1. Add rootfs-$(PLATFORM).yml.in.yq . 
2. When building, call make eve PLATFORM=<device> 

Sample modifiers

To ease in usage, the following is a simple .yq  file for a platform named foo . It adds files to init , an onboot  and long-running services .

.services += {"name": "services-foo","image": "SERVICES_FOO_TAG", "cgroupsPath": "/eve/services/services-foo"} |
.onboot += {"name": "onboot-foo","image": "ONBOOT_FOO_TAG"} |
.init += "BSP_FOO_TAG"

Note the usage of |  to connect independent lines.