GPT instead of MBR in my WKS file


Jonas Vautherin
 

Hello :-),

Learning Yocto with my Pocketbeagle, I have been looking at the WKS file recently. Starting with the default beaglebone-yocto.wks, it is working fine for an MBR partition table:

```
part /boot --source bootimg-partition --ondisk mmcblk0 --fstype=vfat --label boot --active --align 4 --size 16 --sourceparams="loader=u-boot" --use-uuid
part / --source rootfs --ondisk mmcblk --fstype=ext4 --label root --align 4 --use-uuid
bootloader --append="console=ttyS0,115200"
```

Looking at the documentation and some examples online, I wanted to try moving that to a GPT partition table. But whatever I do, I always end up with an image that just does not boot at all (and my FTDI connection does not give me any serial output at all, not even an error). For instance I tried something like this:

```
part /boot --source bootimg-efi --ondisk mmcblk0 --fstype=vfat --label boot --part-name boot --active --align 1024 --sourceparams="loader=grub-efi" --use-uuid
part / --source rootfs --ondisk mmcblk --fstype=ext4 --label root --part-name system --align 1024 --use-uuid
bootloader --ptable gpt --append="console=ttyS0,115200"
```

So I obviously started with `--ptable gpt`, and then gradually tried to change other things (like `bootimg-efi` instead of `bootimg-partition`, changing the `--align` value, etc. Honestly I don't really know what I am doing, but I have not found references that helped me online (probably because I'm a beginner and I do not know what to search for).

I would love to get some insights about this. Like how could I verify if my pocketbeagle can run from GPT at all (I have read that some ROMs do not support it because it is too big)? And does GPT require EFI and/or grub at all, or is that independent?

After all, I would just like to have a GPT partition table that looks very similar to my MBR table, except that with GPT I could benefit from the `--part-name` for fastboot. I don't think I want grub at all, for instance.

Best Regards,
Jonas

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