How to get and customize the bootloader

We are interested in making changes to the ABL, but I’m struggling to find documentation or information on how to do that. I was able to retrieve and build the ABL repository per the ‘How to get and customize the bootloader’ section of the release notes. I was hoping that I could figure out what to do just from the source and build outputs, but I’m not making any progress. Can you please point me to information on how one would go about modifying the ABL and then flashing the modified ABL to the board? Thanks.

hey!

the instructions are slightly misleading. In particular, we forgot to mention that the resulting .elf file must be signed using the Qualcomm signing tools, even though I believe secure boot is not enabled, boot firmware files need to be signed with a test key. Unfortunately these tools are not publicly available but there are most likely available in the BSP from Thundercomm.

From your message it’s not clear what you’ve been able to do for now. You can review our Jenkins build script which generated the files we published, check out our build job:

https://git.linaro.org/ci/job/configs.git/tree/lt-qcom-bootloader-rb5.yaml

which in turn, uses the following script:

https://git.linaro.org/ci/job/configs.git/tree/lt-qcom-bootloader/rb5/builders.sh

Thank you. After reviewing those scripts I think I understand how to deploy any changes, and I believe that I have gained access to the signing tools through ChipCode (though I haven’t tried using it yet).

As for making changes, I’m new to UEFI so I would appreciate any guidance you might have on the best approach. We are looking to configure a chip over I2C, show a splashscreen, and assert a GPIO before launching the kernel.

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I am afraid we might not be able to help too much with ABL/UEFI… we aren’t dealing much with this piece of software ourselves. Maybe someone else on the forum will be able to help… otherwise, you might want to contact Thundercomm to see if they can help…

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