Re: [PATCH v2 2/7] init: add DPS root partition type UUID definitions

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] init: DPS_ROOT_PARTITION_TYPE_UUID sets 64-bit UUID on 32-bit LOONGARCH
--

commit 109ce0d2c6fc812a6bc94f72e97807013dc5fc56
Author: Vincent Mailhol <mailhol@kernel.org>

init: add DPS root partition type UUID definitions

This commit adds the hidden DPS_ROOT_PARTITION_TYPE_UUID string Kconfig
symbol populated with the Discoverable Partitions Specification root
partition type UUIDs for EFI-supported architectures, along with the
derived DPS_ROOT_AUTO_DISCOVERY boolean symbol.

Link: https://uapi-group.org/specifications/specs/discoverable_partitions_specification/

> diff --git a/init/Kconfig b/init/Kconfig
> index b31aa298c4fe5..133854355697b 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -2166,6 +2166,20 @@ config ARCH_HAS_PREPARE_SYNC_CORE_CMD
>  config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
>  	bool
>  
> +config DPS_ROOT_PARTITION_TYPE_UUID
> +	depends on EFI && EFI_PARTITION
> +	string
> +	default "69dad710-2ce4-4e3c-b16c-21a1d49abed3" if ARM
> +	default "b921b045-1df0-41c3-af44-4c6f280d3fae" if ARM64
> +	default "77055800-792c-4f94-b39a-98c91b762bb6" if LOONGARCH

[Severity: Medium]
Should the LOONGARCH default also depend on 64BIT, matching the RISCV &&
64BIT check on the next line?

The UUID 77055800-792c-4f94-b39a-98c91b762bb6 is defined by the
Discoverable Partitions Specification specifically for 64-bit LoongArch
(SD_GPT_ROOT_LOONGARCH64), and the specification does not define a root
partition type UUID for 32-bit LoongArch.

In arch/loongarch/Kconfig, config LOONGARCH unconditionally selects EFI and
supports both 32-bit and 64-bit kernel builds (such as
arch/loongarch/configs/loongson32_defconfig):

arch/loongarch/Kconfig:
config LOONGARCH
    ...
	select EFI
	select GENERIC_ATOMIC64 if 32BIT
    ...
config 32BIT
	bool "32-bit kernel"

config 64BIT
	bool "64-bit kernel"

When building a 32-bit LoongArch kernel (CONFIG_LOONGARCH=y, CONFIG_32BIT=y,
CONFIG_EFI=y, and CONFIG_EFI_PARTITION=y), DPS_ROOT_PARTITION_TYPE_UUID gets
populated with the 64-bit LoongArch UUID and DPS_ROOT_AUTO_DISCOVERY is
enabled. Because a 32-bit LoongArch kernel sets elf_check_arch to
elf32_check_arch in arch/loongarch/include/asm/elf.h and only loads
ELFCLASS32 binaries, wouldn't early_lookup_dps_root() auto-discover and
mount a 64-bit LoongArch root partition when root= is omitted, and then fail
to execute its 64-bit userspace?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261025-discoverable-root_partitions-v2-0-fb77d0821fab@kernel.org?part=2