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[98.61.227.136]) by smtp.gmail.com with ESMTPSA id v6-20020a6b5b06000000b007870289f4fdsm2623774ioh.51.2023.07.14.06.35.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Jul 2023 06:35:42 -0700 (PDT) Message-ID: Date: Fri, 14 Jul 2023 08:35:40 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v14 01/25] docs: gunyah: Introduce Gunyah Hypervisor Content-Language: en-US To: Elliot Berman , Srinivas Kandagatla , Prakruthi Deepak Heragu , Jonathan Corbet Cc: Murali Nalajala , Trilok Soni , Srivatsa Vaddagiri , Carl van Schaik , Dmitry Baryshkov , Bjorn Andersson , Konrad Dybcio , Arnd Bergmann , Greg Kroah-Hartman , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bagas Sanjaya , Will Deacon , Andy Gross , Catalin Marinas , Jassi Brar , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20230613172054.3959700-1-quic_eberman@quicinc.com> <20230613172054.3959700-2-quic_eberman@quicinc.com> <5dc7438c-e161-915c-c037-19c5099a274f@quicinc.com> From: Alex Elder In-Reply-To: <5dc7438c-e161-915c-c037-19c5099a274f@quicinc.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 7/3/23 5:41 PM, Elliot Berman wrote: >> If it's signaled after every message is sent, does it >> indicate that the message has been *received* by VM_B >> (versus just received and copied by Gunyah)? >> > > To connect some dots: the Tx vIRQ is fired when the reader reads a > message and the number of messages still in the queue decrements to the > "not full" threshold. > > https://github.com/quic/gunyah-hypervisor/blob/3d4014404993939f898018cfb1935c2d9bfc2830/hyp/ipc/msgqueue/src/msgqueue_common.c#L142-L148 So the Tx vIRQ on the sender is only fired when the state of the receiver's Rx queue goes from "full" to "not full". Normally there is no signal sent, and a sender sends messages until it gets a "queue full" flag back from a gh_msgq_send() call. At that point it should stop sending, until the Tx vIRQ fires to indicate the receiver queue has "room" (fewer than the "full threshold" messages are consumed). There is no way (at this layer of the protocol) to tell whether a given message has been *received*, only that it has been *sent* (meaning the hypervisor has accepted it). And Gunyah provides reliable delivery (each message received in send order, exactly once). Now that I re-read what you said it makes sense and I guess I just misunderstood. There *might* be a way to reword slightly to prevent any misinterpretation. Thanks. -Alex