[PATCH 00/19] init: discoverable root partitions, a.k.a. an omittable "root=" cmdline option

[Vincent Mailhol]

On 15/06/2026 at 19:04, Al Viro wrote:
> On Mon, Jun 15, 2026 at 06:08:56PM +0200, Vincent Mailhol wrote:
> 
>> Tested with GRUB, which implements the LoaderDevicePartUUID EFI variable
>> in its bli module [3]. With this, I was able to boot a kernel with a
>> completely empty cmdline and no initrd.
>>
>> [1] The Discoverable Partitions Specification (DPS)
>> Link: https://uapi-group.org/specifications/specs/discoverable_partitions_specification/
>>
>> [2] systemd-gpt-auto-generator
>> Link: https://www.freedesktop.org/software/systemd/man/latest/systemd-gpt-auto-generator.html
>>
>> [3] GRUB -- §16.2 bli
>> Link: https://www.gnu.org/software/grub/manual/grub/html_node/bli_005fmodule.html
> 
> So what does that thing, tied to EFI as it is, have to do with architectures where
> 	* firmware is rather unlike EFI

I made CONFIG_DPS_ROOT_AUTO_DISCOVERY depend on CONFIG_EFI for this reason.

> 	* firmware wouldn't know what to do with GPT
> 	* GRUB is *not* ported to, let alone used
> such as, say it, the very first one mentioned at your [1]?

Fair point. I just did:

  $ git grep "^config EFI$"
  arch/arm/Kconfig:config EFI
  arch/arm64/Kconfig:config EFI
  arch/loongarch/Kconfig:config EFI
  arch/riscv/Kconfig:config EFI
  arch/x86/Kconfig:config EFI

Anything not in this list is dead code at the moment.

> Or is that conditional upon "if anyone wants to design replacement firmware
> for those, and if they agree to follow our wishlist"?

No, it was just an oversight from my side. I will just keep arm, arm64,
loongarch, riscv and x86 in my v2.


Yours sincerely,
Vincent Mailhol