From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B2E9A606A31D for ; Thu, 22 Oct 2026 15:26:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=FXTGxYGk; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=O56pynoB DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Reply-To:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Date: Content-Transfer-Encoding:Content-Type:References:In-Reply-To:Cc:To:Subject: From:Message-ID:MIME-Version:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=XE9yWNlXsvGeGCWhIwmUN0zA/ByHkLoM4gSXGnB7k80=; b=FXTGxYGkR0/0qXJZq4+4m7oFvX flQeUukT5BUGSLUQ7qB6BttaSl660h//5V1d46veM/y1CjMXCB3vLaF2IU9MovVy/DlkbrJaUAMVF aeTBScM/U0htfJfJzONOxuVLAL1qNgt8KniGNUNIAAd3cm+YTzGaJpLbnlb9N6mSIYORjvuPf+wAf qWASyAlCV0k2Xv2vNcaYil4R3pxUbb0Hc97hz3Ok0l7EAQK0AStcADwtI72O9JnyDarRZbTfwlO0R TEFFmqQQSmOFLSqIbKBl9mTRUoDEqXw/SydDZmlMQyOKj+3Je5RFvdnB1ibFNuZusk7Cw20+iOeUw Zk2P2oDw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xJugX-0000000EPEl-0SXk; Thu, 22 Oct 2026 15:26:29 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xJugP-0000000EPDN-3V4L for kexec@lists.infradead.org; Thu, 22 Oct 2026 15:26:25 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 47FA260EED; Thu, 22 Oct 2026 15:26:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9442C1F01825; Thu, 22 Oct 2026 15:26:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792682781; bh=XE9yWNlXsvGeGCWhIwmUN0zA/ByHkLoM4gSXGnB7k80=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=O56pynoBI5KpalG2BPlOv25DBE/DEB5Jo16dwWZI1bKpSwVasiwoaBO1B+nBR3eOF YrEtrKJrO9UkWi/jNc1BfYPdxje2j0uU60E6Pg+WdQaOrmL8g4EeCnA0KLeLbCb7i7 er3SvneVxCrxpHGAWPs5GmcYSwXSO7wtrEmLhMyWBHTUVOkYHN0NDjN9GUc9uO6oMY cOzfWrc24kvsxvGG/LnXoNum4o0AxvpJVhyL5kv/WqiNeQ4T0zB4p8n5WLNGwhy2H9 0cVGOxksMK6cJDnWKS8W86VS2dru3kyz6Q+X1EdtUk/iRdG1ew7Tj9iyvnWzBcp+PF 84J3rrpwuU/ng== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH v2 3/4] liveupdate: Replace compatibility string with a 2-bit pair feature header To: "Tarun Sahu" , "Andrew Morton" , joro@8bytes.org, "Mike Rapoport" , "Pratyush Yadav" , maz@kernel.org, arnd@arndb.de, "David Matlack" , jgg@nvidia.com, robin.murphy@arm.com, loganodell@google.com, oupton@kernel.org, kevin.tian@intel.com, alex@shazbot.org, dwmw2@infradead.org, pbonzini@redhat.com, seanjc@google.com, will@kernel.org, "Pasha Tatashin" , "Alexander Graf" , "Bjorn Helgaas" , baolu.lu@linux.intel.com Cc: sagis@google.com, linux-pci@vger.kernel.org, kexec@lists.infradead.org, skhawaja@google.com In-Reply-To: <20261021152527.375070-4-tarunsahu@google.com> References: <20261021152527.375070-1-tarunsahu@google.com> <20261021152527.375070-4-tarunsahu@google.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 22 Oct 2026 15:26:19 +0000 X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Sender: "kexec" X-Spam-Status: No, score=-10.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: > LUO and its file handlers validate handed-over state with monolithic > compatibility strings ("luo-v5", "memfd-v2"). Any change to a serialized > structure, even an optional additive one, must bump the string, which > breaks live update between adjacent kernels. Replace the string in > struct luo_ser with a feature header, so that the target kernel can > accept or reject the source kernel state per feature. >=20 > struct luo_feature_hdr is a fixed 128-byte header: the serialized > structure size from the source kernel followed by 15 chained u64 feature > flags entries. The fixed size keeps payload field offsets identical in > every kernel, regardless of how many flags entries a source kernel uses. >=20 > Each feature has a 2-bit pair (req, active) state (enum luo_feat_state: > LUO_FEAT_DISABLED, LUO_FEAT_OPTIONAL, LUO_FEAT_REQUIRED). A flags entry > holds 31 features, and bits [63:62] =3D 0b11 chain to the next entry (465 > [ ... ] > Future changes add new entries to enum luo_core_feature before > LUO_CORE_FEAT_MAX. >=20 > Signed-off-by: Logan Odell > Signed-off-by: Tarun Sahu Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261021152527.3750= 70-1-tarunsahu@google.com?part=3D3