Re: [PATCH 08/19] parisc: define DPS root partition type UUID

[Helge Deller]

On 6/15/26 22:02, James Bottomley wrote:
> On Mon, 2026-06-15 at 18:09 +0200, Vincent Mailhol wrote:
> > DPS [1] assigns GPT partition type UUIDs to operating system
> > partitions. Root partitions use architecture-specific type UUIDs so
> > the OS can discover the intended root filesystem without relying on a
> > root=  cmdline option.
> >
> > Define DPS_ROOT_PARTITION_TYPE_UUID in asm/dps_root.h for parisc and
> > select ARCH_HAS_DPS_ROOT_PARTITION_TYPE_UUID.

Vincent, first of all thank you for at least trying to including parisc (and other
niche Linux ports) in the specification! (whatever the outcome is!)

> > [1] The Discoverable Partitions Specification (DPS)
> > Link:
> > https://uapi-group.org/specifications/specs/discoverable_partitions_specification/
>
> How are you planning to make this work for parisc?  Some systems have a
> PALO boot partition (fdisk type 0xf0) but the more modern way is to
> place palo inside a hidden ext4 inode in /boot.  The way parisc IODC
> works is very similar to the way MSDOS boots with the palo location
> table in the first block so I theorize that would probably work for gpt
> partitions as well ... I'm just not sure anyone has tested it.
>
> However, to get this to work with PALO for auto discovery, you'd need
> palo patches to recognize the DPS UUID and no-one seems to have
> submitted anything to palo for this.

Maybe it's not necessary that palo does this job?
palo could stay as is and load kernel and the initrd.
Then the kernel (or the scripts in initrd) could try to find the root
partition on it's own (and handle GPT discs).

I even once started porting grub to parisc (which is currently on hold
because I'm busy with other stuff). If I ever finish it, having such a
mechanism/constant already in place is IMHO beneficial.

Helge