Raspberry Pi 3 - Booting from FAT32 on 0x0b vs 0xef partitions

[kallisti5]

Describe the bug
What partition types will the Raspberry Pi 3 boot from? Haiku moved to using 0xef for their boot partition which works on pretty much every SoC we can test on except the Raspberry Pi 3.

To reproduce
Setup an SD card with the following format:

• 0xef EFI System Partition FAT32
  • https://github.com/haiku/firmware/raw/master/u-boot/arm/rpi3/README.md
  • https://github.com/haiku/firmware/raw/master/u-boot/arm/rpi3/config.txt
  • https://github.com/haiku/firmware/raw/master/u-boot/arm/rpi3/u-boot.bin
  • https://github.com/raspberrypi/firmware/raw/07937c7d48bcd44cc1015c6257ae2cfa5da51298/boot/bootcode.bin
  • https://github.com/raspberrypi/firmware/raw/07937c7d48bcd44cc1015c6257ae2cfa5da51298/boot/start.elf
  • https://github.com/raspberrypi/firmware/raw/master/boot/LICENCE.broadcom
• 0xeb Haiku's partition.

Expected behavior
The Raspberry Pi 3 should launch start.elf as usual.

Actual behavior
Green activity LED remains off. Changing the first boot partition from 0xef to 0x0b fixes the issue and u-boot starts as expected.

[pelwell]

If you are referring to the initial step of loading bootcode.bin from the attached storage (usually an SD card, but could be a USB MSD or a TFTP server) then there is no possibility to change the behaviour - that code is in the ROM.

[kallisti5]

@pelwell at minimum, i'm seeing any documentation from Rasberry Pi foundation on what the requirements are for the boot partition. We know the Rpi4 will boot from a partition marked 0x0b or 0xef. It appears that the Rpi3 only boots from 0x0b.

These closed early-loader blobs are annoying

[pelwell]

The ROM does not recognise the 0xef partition type, and there is no possibility to change this. It was a later addition to the Pi 4 EEPROM after a user request (raspberrypi/rpi-eeprom#126).

[kallisti5]

@pelwell thanks for confirming.. I guess we're going to have to add a partition ID change when users try to use our images on the Rpi3.

ARM needs to standardize on EFI... between AllWinner's fixed offsets and Broadcom's blobs the ecosystem is a mess.