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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id af79cd13be357-914f8800e1dsm455621385a.34.2026.05.27.05.36.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2026 05:36:34 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wSDUw-0000000EOYw-0lyZ; Wed, 27 May 2026 09:36:34 -0300 Date: Wed, 27 May 2026 09:36:34 -0300 From: Jason Gunthorpe To: Christian =?utf-8?B?S8O2bmln?= Cc: Zhiping Zhang , Alex Williamson , Leon Romanovsky , Sumit Semwal , Bjorn Helgaas , kvm@vger.kernel.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, Keith Busch , Yochai Cohen , Yishai Hadas Subject: Re: [PATCH v5 0/4] vfio/dma-buf: add TPH support for peer-to-peer access Message-ID: <20260527123634.GK2487554@ziepe.ca> References: <20260526144401.1485788-1-zhipingz@meta.com> <20260527121438.GJ2487554@ziepe.ca> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, May 27, 2026 at 02:23:46PM +0200, Christian König wrote: > Yeah that's a good point, I should probably rephrase the question. > > I'm aware of how TPH works by adding the extra ST to the TLP. > > But my question is how is that useful to a PCIe endpoint? What is the effect of the ST here? TBH I've never heard Meta explain what their device is doing with it. At least it seems to be super important to their device.. Jason