Re: [PATCH 01/15] netlink: specs: Introduce multi-message blobs for SPDM

[Donald Hunter <donald.hunter@gmail.com>]

Dan Williams <djbw@kernel.org> writes:

> The SPDM, Security Protocol and Data Model, underpins PCI device security
> and other use cases. It defines objects that allow for verification of
> device identity and configuration. These objects can be large in size 16MB.
> Netlink is otherwise suitable to define the operations, with optional
> parameters, and notifications for working with these objects. For example,
> operations like "regenerate evidence with nonce", "mark evidence
> validated", and "broadcast evidence / security state change events".
>
> A netlink 'blob' is introduced as a way to teach YNL that one instance of a
> attribute may span multiple messages. It enables netlink to convey all the
> data needed for verification and manipulation of SPDM transported evidence.
>
> The schema change to allows YNL to infer that an attribute may span

change to allows -> change allows

> multiple messages and interrogate its length to preallocate an
> appropriately sized receive buffer.
>
> The design direction to extend the netlink schema for a "multi-message
> object receive" case was the result of this discussion [1].
>
> Cc: Alistair Francis <alistair.francis@wdc.com>
> Cc: Lukas Wunner <lukas@wunner.de>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Donald Hunter <donald.hunter@gmail.com>
> Link: http://lore.kernel.org/20260318170014.6650d2bf@kernel.org [1]
> Signed-off-by: Dan Williams <djbw@kernel.org>
> ---
>  Documentation/netlink/genetlink-legacy.yaml | 6 ++++++
>  Documentation/netlink/genetlink.yaml        | 7 +++++++
>  Documentation/netlink/netlink-raw.yaml      | 7 +++++++

I suggest you drop the changes to genetlink-legacy and netlink-raw
because I don't think we want to support the blob functionality for
legacy families.

Can you also update Documentation/userspace-api/netlink/specs.rst to
describe the multi-attr / bloblen API behaviour.