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Embedded Linux Development Using Yocto Project

You're reading from   Embedded Linux Development Using Yocto Project Leverage the power of the Yocto Project to build efficient Linux-based products

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Product type Paperback
Published in Apr 2023
Publisher Packt
ISBN-13 9781804615065
Length 196 pages
Edition 3rd Edition
Tools
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Authors (2):
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Otavio Salvador Otavio Salvador
Author Profile Icon Otavio Salvador
Otavio Salvador
Daiane Angolini Daiane Angolini
Author Profile Icon Daiane Angolini
Daiane Angolini
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Toc

Table of Contents (20) Chapters Close

Preface 1. Chapter 1: Meeting the Yocto Project 2. Chapter 2: Baking Our First Poky-Based System FREE CHAPTER 3. Chapter 3: Using Toaster to Bake an Image 4. Chapter 4: Meeting the BitBake Tool 5. Chapter 5: Grasping the BitBake Tool 6. Chapter 6: Detailing the Temporary Build Directory 7. Chapter 7: Assimilating Packaging Support 8. Chapter 8: Diving into BitBake Metadata 9. Chapter 9: Developing with the Yocto Project 10. Chapter 10: Debugging with the Yocto Project 11. Chapter 11: Exploring External Layers 12. Chapter 12: Creating Custom Layers 13. Chapter 13: Customizing Existing Recipes 14. Chapter 14: Achieving GPL Compliance 15. Chapter 15: Booting Our Custom Embedded Linux 16. Chapter 16: Speeding Up Product Development through Emulation – QEMU 17. Chapter 17: Best Practices 18. Index 19. Other Books You May Enjoy

Debugging metadata variables

To debug the metadata variables, we can use the bitbake-getvar script. It uses the BitBake internal data to get a specific variable value and its attribution history.

For example, to inspect the PACKAGECONFIG variable for the procps recipe, we can use the following command:

Figure 10.7 – The result of bitbake-getvar -r procps PACKAGECONFIG

Figure 10.7 – The result of bitbake-getvar -r procps PACKAGECONFIG

From Figure 10.7, we can see that PACKAGECONFIG at the end is empty. We can also see that defaultval was set to "${@bb.utils.filter('DISTRO_FEATURES', 'systemd', d)}" at line 33 from the meta/recipes-extended/procps/procps_3.3.17.bb file.

We can see the procps recipe lines 33 and 34 in the following screenshot:

Figure 10.8 - The procps recipe 33 and 34 lines

Figure 10.8 - The procps recipe 33 and 34 lines

The bitbake-getvar script can be used to check whether a feature is enabled or to be sure a variable has been expanded as we expect.

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