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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-5498cb57669sm12221861cf.24.2026.11.02.17.05.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Nov 2026 17:05:38 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1xO2y1-0000000BIml-2jCU; Mon, 02 Nov 2026 21:05:37 -0400 Date: Mon, 2 Nov 2026 21:05:37 -0400 From: Jason Gunthorpe To: Jiri Pirko Cc: linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, david.quigley@intel.com, lukas@wunner.de, ksinyuk@kernel.org, rodrigo.vivi@intel.com, cedric.xing@intel.com, sameo@meta.com, drdeeglaze@gmail.com, James.Bottomley@hansenpartnership.com, aik@amd.com, jpiotrowski@nvidia.com, qinkun@google.com, pgonda@google.com, jic23@kernel.org, alistair.francis@wdc.com, ankita@nvidia.com, suzuki.poulose@arm.com, kas@kernel.org, rick.p.edgecombe@intel.com, elena.reshetova@intel.com, dave.hansen@linux.intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, peter.fang@intel.com Subject: Re: [PATCH RFC 11/20] ctlv: Prepare runtime introspection Message-ID: <20261103010537.GI3889730@ziepe.ca> References: <20261015145053.3664509-1-jiri@resnulli.us> <20261015145053.3664509-12-jiri@resnulli.us> <179302367452.58760.11808905856343064399.b4-review@b4> X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Oct 30, 2026 at 10:53:11AM +0100, Jiri Pirko wrote: > >So.. how about could we drop the sets, use a direct description of the > >layout and do something else for the ID numbering? Maybe the numbering > >can be solved directly by only listing the names in: > > > >numbering: > > - device-get.reply > > - device-get.reply.caps > > - device-get.caps.evidence > > -[..] > > > >? > > I'm still committed to implicit numbering. For "inline records" I > resolved it by having it encoded as a tree with 4 levels: > > 63 48 47 46 45 32 31 28 27 24 23 20 19 16 15 0 > +-------------+-----+------------+------+------+------+------+------------------+ > | family |kind | index | L1 | L2 | L3 | L4 | field | > +-------------+-----+------------+------+------+------+------+------------------+ > |<------------------ record ------------------>| Fascinating idea. Sort of like an oid I guarentee we will run out of bits someday :) I saw recently we ran out of bits in RDMA :\ 3 bits seems like quite a small number.. Maybe increasing op to 128 bits? Maybe family/kind/index/field spread over the first 64 and then the Lx's over the second? At the very least there should be an escape hatch so that if this becomes too small there is a way to opt into some new layout and fix it without breaking everything. Jason