Hi, Some comments below:
> -----Original Message----- > From: edk2-devel [mailto:[email protected]] On Behalf Of > Rafael Machado > Sent: Wednesday, March 28, 2018 9:32 PM > To: [email protected] > Subject: [edk2] NVMe Smart Data Buffer Size > > Hi everyone > > I'am working on a development related to retrieving the SMART data > information from a NVMe device. > After some research I got to a code that works correctly, but I would like > to have a 100% understanding of why it works. > > To retrieve the SMART data I send the command > (EFI_NVM_EXPRESS_COMMAND) as > follows: > > //************************************************************ > //Fill the EFI_NVM_EXPRESS_COMMAND struct > Command->Cdw0.Opcode = NVME_ADMIN_GET_LOG_PAGE_CMD; //This is > the command > 0x02 > Command->Nsid = NVME_ALL_VALID_NSID; //The NSID used in this case is > the 0xFFFFFFFF to retrieve the global information > Command->Cdw10 = (4096 << 16) | 2; // page 2 is the Smart/Health log page > Command->Cdw11 = 0x0; > Command->Cdw12 = 0x0; > Command->Cdw13 = 0x0; > Command->Flags = CDW10_VALID > | CDW11_VALID > | CDW12_VALID > | CDW13_VALID; > > // Fill the EFI_NVM_EXPRESS_PASS_THRU_COMMAND_PACKET struct > This->Nsid = NVME_ALL_VALID_NSID; //This is the NSID used by > the NVME_PROTOCOL, that is also 0xFFFFFFFF > CommandPacket->NvmeCmd = Command; > CommandPacket->NvmeCompletion = Completion; > CommandPacket->TransferBuffer = (VOID*) SmartData; > CommandPacket->TransferLength = 4096; > CommandPacket->CommandTimeout = 0; > CommandPacket->QueueType = NVME_ADMIN_QUEUE; > CommandPacket->MetadataBuffer = NULL; > CommandPacket->MetadataLength = 0; > //************************************************************ > > The question I have, is about the size of the buffer to be used as the > transfer buffer at the EFI_NVM_EXPRESS_COMMAND and at the > EFI_NVM_EXPRESS_PASS_THRU_COMMAND_PACKET. At the Nvme spec we > see that the > SmartData information is 512 bytes long. > > So the question is. > Why, even having just 512 bytes to be retrieved by the GetLogCommand page > 0x02, do I need to create a 4096 bytes buffer to retrieve the SMART data ? I have a check on the NVMe v1.1 spec for the Get Log Page command: For Command Dword 10: 27:16 Number of Dwords (NUMD): This field specifies the number of Dwords to return. If host software specifies a size larger than the log page requested, the results are undefined. This is a 0's based value. Per my understanding, since the field requires a 0's based Dword value, for getting the SMART / Health Information (which is 512 bytes in length), the Cdw10 should be: Command->Cdw10 = (127 << 16) | 2; // 128 Dword, 0's based And for the PassThru command packet: CommandPacket->TransferLength = 512; Please help to verify if this works properly for you. Thanks in advance. > > Command->Cdw10 = (4096 << 16) | 2; > CommandPacket->TransferBuffer = (VOID*) SmartData; (allocated previously) > CommandPacket->TransferLength = 4096; > > Just for reference. When I create a 512 bytes buffer I get a DeviceError > status after the PassThru. With the sample code below: > > Command->Cdw10 = (512 << 16) | 2; > CommandPacket->TransferBuffer = (VOID*) SmartData; (allocated previously) > CommandPacket->TransferLength = 512; > > > Another question I have is: > We have two places that we need to set the Nsid. > > EFI_NVM_EXPRESS_PASS_THRU_COMMAND_PACKET. Nsid > EFI_NVM_EXPRESS_COMMAND.Nsid > > Since I am not a NVme expert, my question is if both represent the same > information. > Should I use 0xFFFFFFFF in both? Yes, you are right. These two values: NamespaceId param for EFI_NVM_EXPRESS_PASS_THRU_PROTOCOL.PassThru() and Nsid field of EFI_NVM_EXPRESS_COMMAND should be set to the same value. Best Regards, Hao Wu > > Thanks and Regards > Rafael R. Machado > _______________________________________________ > edk2-devel mailing list > [email protected] > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
