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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6dfade73406sm9949676d6.78.2025.01.10.07.09.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jan 2025 07:09:02 -0800 (PST) Date: Fri, 10 Jan 2025 10:08:59 -0500 From: Peter Xu To: Tomoyuki HIROSE Cc: qemu-devel@nongnu.org, Paolo Bonzini , David Hildenbrand , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [RFC PATCH 2/5] system/memory: support unaligned access Message-ID: References: <2de74447-00f7-4bcf-81f3-c8461ec19a67@igel.co.jp> <9d1f07e5-2c08-455c-a653-e57e219666ab@igel.co.jp> <1ab0a747-e2c4-4545-bae9-31e19c77bd75@igel.co.jp> <2e2dba3c-2bfc-478a-988d-fbf2e58cc293@igel.co.jp> <6a4dd6ef-9d0c-4f1f-81eb-0d55fa32daf5@igel.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6a4dd6ef-9d0c-4f1f-81eb-0d55fa32daf5@igel.co.jp> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.432, 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_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: 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 Fri, Jan 10, 2025 at 07:11:27PM +0900, Tomoyuki HIROSE wrote: > > > MR implementation to be safe when unaligned accessing (current xHCI > > > implementation does not handle unaligned accesses but the spec allows > > > unaligned accesses). > > > > > > In addition, maybe it would be better to document the constraint that > > > the situation where 'valid.unaligned = true' and 'impl.unaligned = > > > false' is not supported. > > Do you perhaps mean this instead? > > > > valid.unaligned = FALSE && impl.unaligned == TRUE > > > > If so, I agree. I think we could even consider adding an assertion into > > memory_region_init_io() to make sure it won't be set. > > > > Thanks, > > > > I'm sorry if I've misunderstood, but are the following understandings > correct?: > - Need to merge my patch that converts an unaligned access to aligned >   accesses. > - Need to add 'impl.unaligned = true' in the following two places. >   - hw/xtensa/mx_pic.c >   - hw/ssi/npcm7xx_fiu.c > - Add an assertion that to check for invalid patterns, additionally. Yes, all these sound good to me. Thanks, -- Peter Xu