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Iglesias" , berrange@redhat.com, eugene@nuvacore.ai, Ruslan_Ruslichenko@epam.com, takahiro.nakata.wr@renesas.com, philmd@oss.qualcomm.com Subject: Re: [PATCH v2 11/20] hw/core: Implement Remote Port Memory Master bus transactions Date: Tue, 3 Nov 2026 15:55:37 +0200 Message-Id: <20261103135503.71748-1-itai.handler@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260915160044.345788-12-ruslichenko.r@gmail.com> References: <20260915160044.345788-1-ruslichenko.r@gmail.com> <20260915160044.345788-12-ruslichenko.r@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::331; envelope-from=itai.handler@gmail.com; helo=mail-wm1-x331.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Hi Ruslan, On 9/15/26 18:00, Ruslan Ruslichenko wrote: [...] > + rp_write(rp, (void *) &pay, len); > + > + if (!rp_timeout) { > + rsp_slot = rp_dev_wait_resp(rp, in.dev, in.id); Thank you for this series. I have been testing v2 by booting a guest from flash behind a QSPI controller modelled as a Remote Port peer. Every guest access to the memory master waits here for a round trip to the peer, about 16 us, and U-Boot and Linux drain the controller's FIFO one 32-bit word at a time, so a 15 MiB kernel image takes 64 s to load. In my tests, a small read FIFO in the memory master, which the peer fills, makes such reads 13x faster (the kernel image loads in 4.9 s). The peer may send a posted write before its response to a read, and the guest's next reads of that range are then served from the FIFO without a round trip. Would you consider including something like this in v3? I have a working patch on top of v2 (about 140 lines) that I would be glad to send you or post as an RFC, whichever you prefer, and I am happy to test v3. Thanks, Itai