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[173.79.56.208]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-476bb7f31f0sm22865331cf.64.2025.03.14.06.46.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Mar 2025 06:46:42 -0700 (PDT) Date: Fri, 14 Mar 2025 09:46:40 -0400 From: Gregory Price To: Jonathan Cameron Cc: lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [LSF/MM] CXL Boot to Bash - Section 0a: CFMWS and NUMA Flexiblity Message-ID: References: <20250313172004.00002236@huawei.com> <20250314110942.0000476a@huawei.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: <20250314110942.0000476a@huawei.com> On Fri, Mar 14, 2025 at 11:09:42AM +0000, Jonathan Cameron wrote: > > > > I was unaware that we blocked mapping persistent as volatile. I was > > working off the assumption that could be flexible mapped similar to... > > er... older, non-cxl hardware... cough. > > You can use it as volatile, but that doesn't mean we allow it in a CFMWS > that says the host PA range is not suitable for persistent. > A BIOS might though I think. > aaaaaaaaaaaaah this helps. Ok, we can repurpose the hardware, but not the CFMWS. Even more pressure on platforms to get it right :P. > > > > Along with the above note, and as mentioned on discord, I think this > > whole section naturally evolves into a library of "Sane configurations" > > and "We promise nothing for `reasons`" configurations. > > :) Snag is that as Dan pointed out on discord we assume this applies > even without the lock. So it is possible to have device and host > hardware combinations where things are forced to be very non-intuitive. > Right, but i think that falls into "We promise nothing, for `reasons`". At the very least it would give us a communication tool that helps bridge the gap between platform, linux, and end-users. Or it'd just makes it all worse, one of the two. ~Gregory