Re: [PATCH 12/19] x86: define DPS root partition type UUIDs

[Dave Hansen]

On 6/15/26 09:09, Vincent Mailhol wrote:
> +#ifdef CONFIG_X86_64
> +#define DPS_ROOT_PARTITION_TYPE_UUID "4f68bce3-e8cd-4db1-96e7-fbcaf984b709"
> +#else
> +#define DPS_ROOT_PARTITION_TYPE_UUID "44479540-f297-41b2-9af7-d131d5f0458a"
> +#endif

This doesn't make a whole lot of sense to me. 64-bit kernels can run
32-bit userspace just fine.

But this #ifdef as proposed means that only a 32-bit *OR* 64-bit kernel
can auto-discover a given partition.

I kinda think you should just have an array of strings for these things,
maybe glued together with some preprocessor magic. Logically something
like this:

const char* const uuids[] = {
#ifdef CONFIG_ARM64
	"b921b045-1df0-41c3-af44-4c6f280d3fae"
#endif
#ifdef CONFIG_X86_64
	"4f68bce3-e8cd-4db1-96e7-fbcaf984b709",
#endif
#if defined(CONFIG_X86) && defined(CONFIG_COMPAT32)
	"44479540-f297-41b2-9af7-d131d5f0458a",
#endif
...
};

... and then search the array. I honestly don't think you need to
sprinkle UUIDs all over the architectures.

It could probably also be done almost entirely in Kconfig. This could be
in, say block/partitions/Kconfig, or arch/*/Kconfig:

config DPS_ROOT_PARTITION_TYPE_UUID_1
	string
        default "4f68bce3-e8cd-4db1-96e7-fbcaf984b709" if X86_64
	default "b921b045-1df0-41c3-af44-4c6f280d3fae" if ARM64
	...

config DPS_ROOT_PARTITION_TYPE_UUID_2
	string
        default "44479540-f297-41b2-9af7-..." if X86 && COMPAT_32

const char* const uuids[] = {
#ifdef CONFIG_DPS_ROOT_PARTITION_TYPE_UUID_1
	CONFIG_DPS_ROOT_PARTITION_TYPE_UUID_1
#endif
#ifdef CONFIG_DPS_ROOT_PARTITION_TYPE_UUID_2
	CONFIG_DPS_ROOT_PARTITION_TYPE_UUID_2
#endif
...
};

There are a lot of ways to do this. I'm just not a super big fan of the
current proposal.

So, boiling it down:

1. Should more than one UUID be supported per kernel build?
2. Should the UUIDs be defined in arch code or generic code?
3. Kconfig or #ifdefs?