---
title: UserGetDMASpecification
framework: SCSIControllerDriverKit
role: symbol
role_heading: Instance Method
path: scsicontrollerdriverkit/iouserscsiparallelinterfacecontroller/usergetdmaspecification
---

# UserGetDMASpecification

Gets the controller-specific direct memory access (DMA) specification in response to a call from the framework.

## Declaration

```occ
virtual kern_return_t UserGetDMASpecification(uint64_t *maxTransferSize, uint32_t *alignment, uint8_t *numAddressBits, DMAOutputSegmentType *segmentType);
```

## Parameters

- `maxTransferSize`: The maximum allowable transfer size for the controller.
- `alignment`: The required alignment for the controller.
- `numAddressBits`: The number of bits that the hardware uses on its internal address bus.
- `segmentType`: On return, set this output segment type according to the endianness of the hardware.

## Return Value

Return Value A value that indicates the result of getting the DMA specification. kIOReturnSuccess indicates success. For error definitions, see IOKit Constants.

## See Also

### Managing direct memory access

- [DMAOutputSegmentType](scsicontrollerdriverkit/dmaoutputsegmenttype.md)