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b=o2aAKF9+YecDzzGk4bV1bgV0jRjVUpJLhAYO7F+KOkCHqua5bwkkqaIW2TcKzIbVH 8RrypZah37W8SoLFH+cHTWDJSt7g97GkpFDUJwpOa8fXEP+C7Fk6eZGhN5bZ5QIWGv rNolRUfDXYPxamX3x3K99oNFg+prs8oECrVd82aJgQ4n1vZ2k1l/hIbRyzuBfF8uiT SP3N1MJ5SlYTbuy72JItmaVx0qM0W054SYKcPl3aN0rEaY1nttQPHOG1KwcWmsiT9y t6SsJiUY3zhw8E+wDnL4kBJBk7lTf7M92W7m9dew6fxdbCTR+FrT6wxWeM+LVgDM2r 6NmZ515+KqNWw== Date: Sun, 15 Nov 2026 20:01:37 +0200 From: Mike Rapoport To: Tarun Sahu Cc: Pasha Tatashin , robin.murphy@arm.com, maz@kernel.org, will@kernel.org, David Matlack , Alexander Graf , seanjc@google.com, jgg@nvidia.com, loganodell@google.com, arnd@arndb.de, dwmw2@infradead.org, baolu.lu@linux.intel.com, Bjorn Helgaas , oupton@kernel.org, alex@shazbot.org, gle.com@google.com, pbonzini@redhat.com, Andrew Morton , kevin.tian@intel.com, joro@8bytes.org, kvmarm@lists.linux.dev, linux-pci@vger.kernel.org, Pratyush Yadav , kexec@lists.infradead.org, kvm@vger.kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, skhawaja@google.com, sagis@google.com, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 05/19] kho: Add feature header for fine-grained ABI compatibility Message-ID: References: <20261110050202.529473-1-tarunsahu@google.com> <20261110050202.529473-6-tarunsahu@google.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261110050202.529473-6-tarunsahu@google.com> X-Stat-Signature: hcdrsx9ion3hkc4uaa8d8wif38pe6nnj X-Rspamd-Queue-Id: AB79C1C0009 X-Rspam-User: X-Rspamd-Server: rspam08 X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1794765712-679143 X-HE-Meta: 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 Kt4tQFiT YU3Q2i3a3zKwM+KoXFyOBLLz2lqvXlYi0rLzeeLdeO1dQFm44+XntG5bH9K0SqnfWfj2U0WfOedF4pZJAErh9M/fG7N4e15h8QBpbcpiffMLHe5sXEuBVGS/ZHzibXSLc2AWHMQM+iDOjDM4dseGZi6Zah5HZbU7+qY0oxe3UB6zNBOrrXmQ+cmcaiaCJYcYCrgVwLJcYfHPq1Xl3dwP6RCN4GArZAmwxbQ4JF9ry1wlD9XfRr7wxqA7ElaJEJIO7L+9O Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Nov 10, 2026 at 05:01:48AM +0000, Tarun Sahu wrote: > > Each subsystem registers its serialized structure with: > > DECLARE_KHO_SER(name, payload_size, nr_required, nr_optional) > > This establishes compile-time assertions and provides type-checked > helpers: kho_ser_size() for total allocation size, kho_ser_init() to > initialize the header, kho_ser_payload() to access the typed payload at > its dynamic offset, and kho_ser_validate() to validate required features > during restoration. DECLARE_KHO_SER_HDR(name, *fhdr) declares a struct > kho_ser_hdr pointer while verifying at compile time that name was > registered with DECLARE_KHO_SER(), allowing callers to document which > structure a feature header pointer represents. > > An example demonstrating how a hypothetical structure defines its > features: > > enum foo_ser_required { > FOO_SER_REQ_BAR, > __FOO_SER_NR_REQUIRED, > }; > > enum foo_ser_optional { > FOO_SER_OPT_BAZ, > __FOO_SER_NR_OPTIONAL, > }; > > struct foo_ser { > __u64 base; /* base fields, always present */ > __u64 bar; /* FOO_SER_REQ_BAR */ > __u64 baz; /* FOO_SER_OPT_BAZ */ > }; > > DECLARE_KHO_SER(foo_ser, 24, The example should have included 7 fields total to make it 42 ;-) Seriously, this magic number show must stop. > __FOO_SER_NR_REQUIRED, __FOO_SER_NR_OPTIONAL); > -- Sincerely yours, Mike.