This section will cover the meta-gemstone Yocto project, which is used to compile the Kernel, Bootloader, Firmware, BSP (Board Support Packages), and Initrd (Init Ramdisk) components for Gemstone development boards.
By the end of this section, you will have knowledge about the following topics:
  • The structure of Yocto projects for Gemstone
  • How Yocto compilation processes are performed
To perform a Yocto build, run the following commands in order: devbox shell —> task box —> task yocto:build.
The Taskfile expects only the MACHINE variable from you for Yocto builds. If no assignment is made, intel-corei7-64 is selected by default.
Example
task yocto:build MACHINE=t3-gem-o1
When the above command is executed, Yocto will perform various download, compilation, and packaging operations to generate the initrd image, kernel, bootloader, and firmware for the selected machine. If this is the first time the process is initiated, it may take up to an hour, depending on your internet speed, CPU power, and RAM capacity. Since Yocto caches intermediate processes on disk, subsequent builds will complete much faster.

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1. meta-gemstone

All Yocto-specific developments for Gemstone are consolidated in the meta-gemstone layer. To preserve Yocto’s modular structure and enable quick adaptation to layer updates, no modifications should be made to . Instead, desired recipes should be customized in the meta-gemstone layer using Yocto’s .bbappend files.

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1.1. Folder Structure

meta-gemstone
|-- conf
|   |-- distro
|   |-- machine
|   |-- templates
|-- recipes-connectivity
|-- recipes-core
|   |-- images
|-- recipes-devtools
|-- recipes-graphics
|-- recipes-kernel
|-- ...
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conf/
This folder contains distribution configurations, , and machine-specific configuration templates.
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recipes-core/images/
Definitions for which packages initrd and other images will include, along with their requirements and features, are specified in .bb recipe files located in this folder.
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recipes-*/
All other folders starting with recipes- are used to categorize recipes. .bbappend files, which allow customization of recipes written in other layers, are typically stored in these folders.

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2. Yocto Outputs

During the build process, Yocto can package almost all projects in DEB, IPK, or RPM formats. Since Gemstone is Debian-based, it has been deemed appropriate to package projects compiled for the Gemstone distribution in DEB format.
You can access the generated packages in the <sdk-directory>/build/yocto/tmp-musl/deploy/deb/<machine-name> folder.
The DEB packages generated by Yocto are used in two areas of the Gemstone distribution:

Debos

When creating the Gemstone image, Debos retrieves files such as the kernel, bootloader, firmware, device-tree, and initrd from the DEB packages generated by Yocto and places them in the /boot directory.

Gemstone APT Server

Machine-specific DEB packages, such as kernel modules, initrd, bootloader, and firmware, are produced by Yocto and uploaded to the Gemstone APT server.