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[173.197.98.118]) by smtp.gmail.com with ESMTPSA id g8-20020a1709026b4800b0017fe9b038fdsm13383998plt.14.2023.02.02.02.56.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 02 Feb 2023 02:56:22 -0800 (PST) Message-ID: <2e85fdea-9ffc-9a20-1c61-45ddd17a7fd6@linaro.org> Date: Thu, 2 Feb 2023 00:56:18 -1000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: An issue with x86 tcg and MMIO To: Jonathan Cameron Cc: =?UTF-8?Q?J=c3=b8rgen_Hansen?= , Ajay Joshi , qemu-devel , Sid Manning References: <78bc53e3-bad3-a5c3-9e53-7a89054aa37a@wdc.com> <20230202093911.000053cb@Huawei.com> Content-Language: en-US From: Richard Henderson In-Reply-To: <20230202093911.000053cb@Huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::635; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x635.google.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 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, NICE_REPLY_A=-0.09, RCVD_IN_DNSWL_NONE=-0.0001, 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 2/1/23 23:39, Jonathan Cameron wrote: > Not sure - if we can do the handling above then sure we could make that change. > I can see there is a path to register the callbacks but I'd kind of assumed > ROM meant read only... I think "romd" means "read mostly". In the case of flash, I believe that a write changes modes (block erase something something) and the region changes state into MMIO. But normal state is read mode where read+execute go through unchallenged. It has been a long time since I studied how all that works, so I may well have forgotten something. r~