EFI backend partitions by UUID

[ejoerns]

Saw your question on #barebox about using EFI with barebox state.

A working example for using a fixed partition as storage backend for state I have is:

state: state {
        magic = <0x3f2ba231>;
        backend-type = "raw";
        backend = <&state_part>;
        backend-stridesize = <4096>;
        #address-cells = <1>;
        #size-cells = <1>;

        [...]
 }

partitions {
        compatible = "fixed-partitions";
        #address-cells = <1>;
        #size-cells = <1>;

        state_part: state {
                partuuid = "14367da7-c518-499f-9aad-e1f366692363";
        };
};

The partition in my case is crated with a script calling sfdisk:

sfdisk -X gpt /dev/sdX << EOF
start=2048,size=18432,type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B,bootable
start=20480,size=2048,uuid=14367da7-c518-499f-9aad-e1f366692363
[...]
EOF

[pvizeli]

Thanks a lot. I have no a working base :)
I used sgdisk.

[pvizeli]

Do you know, how I can pass the devicetree to linux kernel on EFI?

I work on:
https://github.com/home-assistant/hassio-os/tree/fix-rauc

[ejoerns]

This is not really supported yet, mainline. But it might be a generic use case so we should think about mainline support, too.

Our current approach is to place the dtb in the EFI partition and point the barebox-state tool to this location.

ATM, this requires a RAUC patch similar to this: https://gist.github.com/ejoerns/13f9d8b594f6816fdca0b8a4d531fc7d

[pvizeli]

Thanks. I will do it like:

On amd64 I patch the barebox host utility to use the /mnt/boot/efi/barebox/state.dtb (the hassio path). So it runs like other architecture and I can use the same rootfs.

[pvizeli]

@ejoerns do you have also a patch for https://git.pengutronix.de/cgit/tools/dt-utils/tree/src/barebox-state.c ?

Edit:
https://git.pengutronix.de/cgit/tools/dt-utils/commit/?h=v2017.03.0/topic/efi-state&id=405590bdb7ae434798010458e810c415e4e99db4