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Device Firmware

Device firmware are binary blobs containing code that are executed by device hardware. The binary blob is available in the driver's namespace for loading.

Device firmware are stored in CIPD (Chrome Infrastructure Package Deployment) and mirrored in Google Storage.

Create a Firmware Package

To create a firmware package, create a directory containing the following files:

README.fuchsia must contain at least the following directives:

  • Name
  • Version
  • Upstream Git
  • License
  • License File

If this is the first time you uploaded to CIPD from the host system, authenticate with CIPD:

fx cipd auth-login

Upload and tag the package in CIPD using the following command:

fx cipd create -in <package-directory> -install-mode copy \
    -name <package-name> \
    -tag git_repository:<source-git-repositry> \
    -tag git_revision:<source-git-revision>

package-name has the format fuchsia/firmware/<name>.

<name> should be a string that identifies the firmware. It may contain any non-whitespace character. It is helpful to identify the driver that will use the firmware in the name.

After this step, the package is uploaded to CIPD. Check the CIPD browser here for packages under fuchsia/firmware.

Adding the Firmware Package to the Build

Add the following entry in prebuilt/zircon.ensure:

@Subdir firmware/<name>
<package-name> git_revision:<source-git-revision>

Where <name>, <package-name> and <source-git-revision> matches the values passed to cipd create above. The package will be downloaded to the path specified by @Subdir under prebuilt, i.e. prebuilt/firmware/<name>.

Next, update prebuilt/zircon.versions with the following command:

scripts/download-prebuilt --resolve

Upload this change to Gerrit and send it to the CQ. The firmware package will be downloaded by scripts/download-prebuilt along with the toolchain and QEMU.

Using the Firmware Package in the Driver

Add the following line to the driver's rules.mk:

MODULE_FIRMWARE := <name>/<path-to-binary-blob>

This will install the firmware to bootfs under /boot/lib/firmware/$(basename $(MODULE_FIRMWARE)).

The load_firmware() API, defined in driver.h loads the firmware pointed to by the path in a VMO.