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Wed, 08 Jul 2026 06:48:37 -0700 (PDT) From: Donald Hunter To: Dan Williams Cc: linux-coco@lists.linux.dev, linux-pci@vger.kernel.org, driver-core@lists.linux.dev, ankita@nvidia.com, Alistair Francis , Lukas Wunner , Jakub Kicinski Subject: Re: [PATCH 01/15] netlink: specs: Introduce multi-message blobs for SPDM In-Reply-To: <20260705220819.2472765-2-djbw@kernel.org> Date: Wed, 08 Jul 2026 12:13:57 +0100 Message-ID: References: <20260705220819.2472765-1-djbw@kernel.org> <20260705220819.2472765-2-djbw@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Dan Williams 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 > Cc: Lukas Wunner > Cc: Jakub Kicinski > Cc: Donald Hunter > Link: http://lore.kernel.org/20260318170014.6650d2bf@kernel.org [1] > Signed-off-by: Dan Williams > --- > 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.