As my first post seems to have disappeared into the void, :), I thought I would try a few more questions. First, may I say that I am coming from a Linux background and know next to nothing about Android.
What tool is used to generate the gpt_*.bin files in dragonboard-820c-bootloader-ufs-linux-31?
The closest I can get is with fdisk. It is the only tool I know which lets you set the block size of a loop-backed file. However, it insists on starting partitions on 1MB, or 256 block, boundaries. Gdisk will let you change the sector alignment but does not let you change the sector size and loop devices seem to have a sector size of 512. Also, fdisk does not allow you to change the number of partition entries from the default 128. However, both tools do set the correct value of 0x000200 for StartingCHS in the PMBR.
Is there any particular reason for the number of partition entries being the smallest multiple of 4 greater than or equal to the number of actual partitions?
The rootfs partition should have a type GUID of ‘Linux root (ARM-64)’.
The partition type GUIDs in the gpt_*.bin files seem to be random, or are they just internal to Qualcomm?