[systemd-devel] How to apply for partition type GUID for Linux /boot?

[Paul Menzel]

Dear Arseny,


On 2019-11-28 15:10, Arseny Maslennikov wrote:
> On Wed, Nov 27, 2019 at 01:13:52PM +0100, Lennart Poettering wrote:
>> On Mi, 27.11.19 12:43, Paul Menzel (pmenzel+systemd-devel at molgen.mpg.de) wrote:
>>
>>> Dear systemd folks,
>>>
>>> A partition type GUID [1] for the partition to be mounted under `/boot`
>>> when started with Linux would be nice. For example, there is already one
>>> for FreeBSD /boot [2].
>>>
>>> As you seem to have requested one for the freedesktop.org shared boot
>>> loader partition already, could you please share the application process
>>> for such a partition type GUID?
>>
>> The great thing about UUIDs are that they are an unmanaged
>> namespace. Anyone can pick one, as long they generate them properly
>> (which today means pulling from a good /dev/urandom).
>>
>> Hence there's no requesting or registration, you just pick one,
>> that's it.
>>
>> I don't know what you expect /boot to be. In the systemd context we
>> defined the "extended boot loader partition", which is a place you can
>> place kernels and stuff, if you don't want to use the EFI ESP for
>> that, and sd-boot and our userspace tools look in it too. It's
>> automatically discovered and mounted to /boot if it exists, by
>> systemd-gpt-auto-generator.
>>
>> This extended boot loader partition as GPT type UUID
>> bc13c2ff-59e6-4262-a352-b275fd6f7172 and that's documented in the
>> systemd-gpt-auto-generator(8) man page.
> 
> The spec at freedesktop.org[1], (naturally) being the first Google hit
> for "discoverable partitions spec" and also being referred to from a lot
> of places all over the community[2][3][4][5][6], has no mention of the
> extended boot loader partition.
> I did not find it at systemd.io (which is, AFAIK, generated from the
> source).
> Is the page unmaintained? If it is: was it moved? are there any
> official, maintained pages for the spec visible and citable on the web?

Isn’t it [7]?

> Otherwise, if the OS is installed on a disk with GPT disk label, and
> if the ESP partition already exists but is too small, a new suitably
> sized (let’s say 500MB) partition with GPT type GUID of
> bc13c2ff-59e6-4262-a352-b275fd6f7172 shall be created and it should
> be used as $BOOT.

Do you mean the term is missing there?


Kind regards,

Paul


> [1]https://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/
> 
> [2]https://forum.manjaro.org/t/discoverable-partitions-specification/104505
> [3]https://lists.freedesktop.org/archives/systemd-devel/2014-March/017817.html
> [4]https://en.wikipedia.org/wiki/GUID_Partition_Table
> [5]https://www.freedesktop.org/software/systemd/man/systemd-gpt-auto-generator.html
> [6]https://wiki.archlinux.org/index.php/GPT_fdisk
[7]: https://systemd.io/BOOT_LOADER_SPECIFICATION

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