Support for Zero 2?

[1nikolas]

As far as I know, the Raspberry PI Zero 2 has the same SoC as the 3 lineup. I tried to use the current version of the firmware on my Ζero 2 W. It boots to the setup/efi shell but can't read the SD card. Is this something that can be easily fixed?
Thanks

The SoC is BCM2710A1 as far as I know

Selecting this does nothing

Boot from file finds no partition

Edit:
EFI boot works perfectly fine with a usb stick so it seems to be an sdcard problem

[alsldlflglhljlk]

Does your SD card have an ESP properly formatted as FAT32?

[1nikolas]

Does your SD card have an ESP properly formatted as FAT32?

I don't even remember what I did one year ago 😅 I'll check again some time

[bradfa]

I also observe this issue when using UEFI firmware v1.39 on a Zero 2W. On a micro-SD card the UEFI fails to locate the EFI system partition on the SD card, but when booting this same disk image on a USB thumb drive then the UEFI finds the ESI system partition on the USB thumb drive without issue.

This seems to rule out incorrect FAT type being the root cause and indicates to me that something in the firmware is not correctly exposing the SD card interface to the UEFI on the Zero 2W.

[bradfa]

Simply adding the bcm2710-rpi-zero-2-w.dtb device tree blob, which should support the zero 2w, results in it getting picked up by the firmware:

MESS:00:00:02.326765:0: dtb_file 'bcm2710-rpi-zero-2-w.dtb'
MESS:00:00:02.334633:0: brfs: File read: /mfs/sd/bcm2710-rpi-zero-2-w.dtb
MESS:00:00:02.339730:0: Loaded 'bcm2710-rpi-zero-2-w.dtb' to 0x1f0000 size 0x8380

As compared to previously (the latest tag of this repo) booting without that dtb file where the firmware cannot find the right dtb:

MESS:00:00:02.327036:0: dtb_file 'bcm2710-rpi-zero-2-w.dtb'
MESS:00:00:02.331108:0: dtb_file 'bcm2710-rpi-zero-2.dtb'
MESS:00:00:02.336228:0: dtb_file 'bcm2837-rpi-zero-2-w.dtb'
MESS:00:00:02.341514:0: Failed to load Device Tree file '?'

But sadly this isn't enough to get the SD card functional as an EFI boot device.

Building current EDK2 master branch, where they've recently fixed the network booting issues on Raspi platforms, results in the debug build complaining that it cannot find an Ethernet interface (because zero 2w doesn't have one) and stopping:

FixEthernetAliases: failed to locate 'ethernet[0]' alias
ASSERT [FdtDxe] UefiLibPrint.c(63): Console != ((void *) 0)

So it looks like proper zero 2w support is going to require some changes in EDK2 to properly support using the SD card and disabling the checks about Ethernet.

[keixthb]

@bradfa @1nikolas How were you able to achieve this? I've tried formatting a micro sd card with both fat32 and fat16 partitions, as well as a USBA drive, and was unable to load the EFI screen. I tried the latest version (v1.39), a previous version (v1.38) and an older version (v1.29). Each version tested will consistently boot to the rainbow screen, but does not proceed to the EFI.

I'm using the msdos (mbr) partition table.

Surely, I must be doing something wrong. Can you please help me? I'm also trying to use the Raspberry pi zero 2w.

[1nikolas]

@bradfa @1nikolas How were you able to achieve this? I've tried formatting a micro sd card with both fat32 and fat16 partitions, as well as a USBA drive, and was unable to load the EFI screen. I tried the latest version (v1.39), a previous version (v1.38) and an older version (v1.29). Each version tested will consistently boot to the rainbow screen, but does not proceed to the EFI.

I'm using the msdos (mbr) partition table.

Surely, I must be doing something wrong. Can you please help me? I'm also trying to use the Raspberry pi zero 2w.

The sd does not currently work and the usb I think will be too slow.. Or is it not?

[bradfa]

@bradfa @1nikolas How were you able to achieve this? I've tried formatting a micro sd card with both fat32 and fat16 partitions, as well as a USBA drive, and was unable to load the EFI screen. I tried the latest version (v1.39), a previous version (v1.38) and an older version (v1.29). Each version tested will consistently boot to the rainbow screen, but does not proceed to the EFI.

I'm using the msdos (mbr) partition table.

Surely, I must be doing something wrong. Can you please help me? I'm also trying to use the Raspberry pi zero 2w.

I'm just using the UART, not any HDMI connection.

When creating the partition table for the SD card, both a GPT partition table and also an MBR partition table are used. The MBR table only calls out the first partition so that the boot firmware can find its file. The GPT partition table calls out all the partitions so that EFI can properly locate things. Often this is referred to as a "protective MBR" but in this case it's used slightly differently than normal. A good overview of this idea is: https://www.eisfunke.com/posts/2023/uefi-boot-on-raspberry-pi-3.html

Sorry, I haven't had time yet to look into the modifications needed for updating EDK2 to support the Pi Zero 2W.

[keixthb]

Thank you, I will try again tomorrow and see if I can get it running. Ideally, my end goal would be installing a server instance of RHEL on the device.