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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c6a71c083esm1471036185a.17.2026.01.22.10.02.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jan 2026 10:02:53 -0800 (PST) Date: Thu, 22 Jan 2026 13:02:52 -0500 From: Gregory Price To: Robert Richter Cc: Alison Schofield , Vishal Verma , Ira Weiny , Dan Williams , Jonathan Cameron , Dave Jiang , Davidlohr Bueso , Jonathan Corbet , linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, "Fabio M. De Francesco" , Terry Bowman , Joshua Hahn , linux-doc@vger.kernel.org Subject: Re: [PATCH v4 3/3] Documentation/driver-api/cxl: ACPI PRM Address Translation Support and AMD Zen5 enablement Message-ID: References: <20260122172432.369215-1-rrichter@amd.com> <20260122172432.369215-3-rrichter@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260122172432.369215-3-rrichter@amd.com> On Thu, Jan 22, 2026 at 06:24:29PM +0100, Robert Richter wrote: > + > +The following changes to the specification are needed: > + > +* Allow a CXL device to be in an HPA space other than the host's address space. > + > +* Allow the platform to use implementation-specific address translation when > + crossing memory domains on the CXL.mem path between the host and the device. > + > +* Recommend that the platform provide a method for the OS to convert device > + addresses to SPAs, such as a PRM handler or _DSM. Document _DSM as the > + preferred method. > + > +* Specify that the kernel (Operating System) determines Endpoint SPA ranges and > + interleaving configurations using platform-specific address translation > + methods. > + As-written for the state of things - this is fine. Just making a note given feedback on the translation patch set here: https://lore.kernel.org/linux-cxl/697186008aa26_1d6f10061@dwillia2-mobl4.notmuch/ If the spec is updated to include such translation tables as described in the discussion above, then this should probably be updated to say: --- Platform shall provide the appropriate CEDT translation tables. If the translation mechanism can't be encoded into tables, then it's on the platform to justify this and provide PRM or _DSM (etc etc.). --- ~Gregory