How to access physical address from a DriverKit driver?

Question

Now I am trying to write an IOUserSCSIParallelInterfaceController driver which uses neither DMA nor PCI and emulates a SCSI target.

I realized that fBufferIOVMAddr ( https://developer.apple.com/documentation/scsicontrollerdriverkit/scsiuserparalleltask/3555105-fbufferiovmaddr ) in SCSIUserParallelTask struct given via UserProcessParallelTask method indicates a physical address and it couldn't be used as a memory address in the driver's memory space.

I need my driver to write something to the buffer and read something from the buffer because I want to make a SCSI Communication by my driver codes.

Is there any way to access memory in physical address from a DriverKit driver?

• yuuzi41: I hope UserGetDataBuffer ( developer.apple.com/documentation/scsicontrollerdriverkit/… ) method can be what helps me, but I'm not sure of that because there is no description so far.

Answer 1

#if ARCMSR_DEBUG_UserGetDataBuffer
 if(pCCB->arcmsr_request.Cdb[0]==0xA0)/*SCSI_CMD_REPORT_LUN*/
 {
 IOBufferMemoryDescriptor *osdatabuffer = nullptr;
 uint64_t address, len, length=pCCB->request_transfer_count; /* parallelTask.fRequestedTransferCount */
 /*
 ******************************************************************************************************************************************
 **
 ** virtual kern_return_t UserGetDataBuffer(SCSIDeviceIdentifier fTargetID, uint64_t fControllerTaskIdentifier, IOBufferMemoryDescriptor **osdatabuffer);
 **
 ******************************************************************************************************************************************
 */
 if((UserGetDataBuffer(fTargetID, pCCB->fControllerTaskIdentifier, &osdatabuffer) != kIOReturnSuccess) || (osdatabuffer == NULL))
 {
 arcmsr_debug_print("ArcMSRUserSpaceDriver %d: ************************************************************************************ \n",ivars->adapter_index);
 arcmsr_debug_print("ArcMSRUserSpaceDriver %d: ** Get task data buffer error, ftargetID=%d fControllerTaskIdentifier=%d \n",ivars->adapter_index,(int)fTargetID,(int)pCCB->fControllerTaskIdentifier);
 arcmsr_debug_print("ArcMSRUserSpaceDriver %d: ************************************************************************************ \n",ivars->adapter_index); 
 goto command_completion;
 }
 if((osdatabuffer->Map(0, 0, 0, 0, &address, &len) != kIOReturnSuccess) || (length != len))
 {
 arcmsr_debug_print("ArcMSRUserSpaceDriver %d: ************************************************************************************ \n",ivars->adapter_index);
 arcmsr_debug_print("ArcMSRUserSpaceDriver %d: ** Map task data buffer error, ftargetID=%d fControllerTaskIdentifier=%d \n",ivars->adapter_index,(int)fTargetID,(int)pCCB->fControllerTaskIdentifier);
 arcmsr_debug_print("ArcMSRUserSpaceDriver %d: ************************************************************************************ \n",ivars->adapter_index); 
 goto command_completion;
 }
 /*
 *******************************************************************************************************************
 ** The LUN LIST LENGTH field shall contain the length in bytes of the LUN list that is available to be transferred.
 ** The LUN list length is the number of logical unit numbers in the logical unit inventory multiplied by eight.
 *******************************************************************************************************************
 */
 memset((void *)(address+3),8,1); /* report_lun_data */
 memset((void *)(address+8),0,8); /* first lun */
 response.fBytesTransferred = 16;
 }
#endif

• Community: Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
• erich: This function is released in DriverKit 21.0 sdk, You can see it in Xcode 13.04 beta
• erich: MacOSX 12.0 has added this function

Answer 2

kern_return_t ArcNVMeUserSpaceDriver::arcnvme_parallelTask_remap_os_data_buffer(SCSIUserParallelTask *pParallelTask, PCCB pCCB)
{
 IOBufferMemoryDescriptor* data_buffer_memory_descriptor = nullptr;
 if ((UserGetDataBuffer(pParallelTask->fTargetID, pParallelTask->fControllerTaskIdentifier, &data_buffer_memory_descriptor) == kIOReturnSuccess) && (data_buffer_memory_descriptor != NULL))
 {
 IOAddressSegment data_buffer_virtual_address_segment = { 0 };
 if (data_buffer_memory_descriptor->GetAddressRange(&data_buffer_virtual_address_segment) == kIOReturnSuccess)
 {
 IOAddressSegment data_buffer_physical_address_segment = { 0 };
 IODMACommandSpecification dmaSpecification;
 IODMACommand* data_buffer_iodmacommand = { 0 };
 bzero(&dmaSpecification, sizeof(dmaSpecification));
 dmaSpecification.options = kIODMACommandSpecificationNoOptions;
 dmaSpecification.maxAddressBits = 64;
 if (IODMACommand::Create(ivars->pciDevice, kIODMACommandCreateNoOptions, &dmaSpecification, &data_buffer_iodmacommand) == kIOReturnSuccess)
 {
 uint64_t dmaFlags = kIOMemoryDirectionInOut;
 uint32_t dmaSegmentCount = 1;
 pCCB->data_buffer_iodmacommand = data_buffer_iodmacommand;
 if (data_buffer_iodmacommand->PrepareForDMA(kIODMACommandPrepareForDMANoOptions, data_buffer_memory_descriptor, 0/*offset*/, pParallelTask->fRequestedTransferCount/*length*/, &dmaFlags, &dmaSegmentCount, &data_buffer_physical_address_segment) == kIOReturnSuccess)
 {
 pParallelTask->fBufferIOVMAddr = (uint64_t)data_buffer_physical_address_segment.address; /* data_buffer_physical_address: overwrite original fBufferIOVMAddr */
 pCCB->OSDataBuffer = reinterpret_cast <uint8_t*> (data_buffer_virtual_address_segment.address);/* data_buffer_virtual_address */
 }
 else
 {
 return (kIOReturnError);
 }
 }
 else
 {
 return (kIOReturnError);
 }
 }
 else
 {
 return (kIOReturnError);
 }
 }
 else
 {
 return (kIOReturnError);
 }
 return(kIOReturnSuccess);
}