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[80.230.79.166]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483b820def3sm55218065e9.2.2026.02.24.08.30.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Feb 2026 08:30:19 -0800 (PST) Date: Tue, 24 Feb 2026 11:30:16 -0500 From: "Michael S. Tsirkin" To: Ankit Agrawal Cc: Jason Gunthorpe , Jonathan Cameron , Igor Mammedov , Vikram Sethi , Shameer Kolothum Thodi , "alex@shazbot.org" , "anisinha@redhat.com" , Aniket Agashe , Neo Jia , Kirti Wankhede , "Tarun Gupta (SW-GPU)" , Zhi Wang , Matt Ochs , Krishnakant Jaju , "qemu-devel@nongnu.org" Subject: Re: [PATCH v1 1/1] hw/acpi/pci.c: preserve generic initiator insertion order Message-ID: <20260224112907-mutt-send-email-mst@kernel.org> References: <20260223082804.0d293861@imammedo> <20260223104411.57a815fa@imammedo> <20260223111302.00000081@huawei.com> <20260224085955-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -10 X-Spam_score: -1.1 X-Spam_bar: - X-Spam_report: (-1.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.358, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.659, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Feb 24, 2026 at 04:22:56PM +0000, Ankit Agrawal wrote: > >> Now the kernel parse it in the sequence of their occurrence. A jumbled up > >> sequence thus results in a jumbled up assignment. > > > > But what is the actual failure mode here? So the numa IDs are all in a > > weird order, what goes wrong from that? > > This interferes with the ability to replicate the numa distance topology > on host in the VM through qemu command line. > > E.g. consider a NUMA system with 2 sockets each with a GPU. > 0,1 are the node ids for the sysmem on socket 0,1 respectively and > 2,3 are the node ids for the GPU memory on socket 0,1 respectively > dist(0,2) = X > dist(0,3) = Y > > If we try to replicate this for the VM by passing qemu arguments with > 4 numa nodes and assign numa distances similar to host, and for the > sake of example qemu mixes up by putting GI for 3 over 2. The SLIT > which sets up the distances do it considering the original order in the > qemu command line. > https://github.com/qemu/qemu/blob/stable-10.2/hw/acpi/aml-build.c#L2040 > > This would lead to a different numa config in terms of distance within > the VM that the one intended through the qemu command line. > > Thanks > Ankit Agrawal but this is not how SLIT is formatted, is it? it does not refer to entries by their location in the table, or am I confused?