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  "identifier" : "/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserGetDMASpecification",
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  "title" : "UserGetDMASpecification"
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# UserGetDMASpecification

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

```
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

A value that indicates the result of getting the DMA specification. <doc://com.apple.documentation/documentation/DriverKit/kIOReturnSuccess> indicates success. For error definitions, see <doc://com.apple.documentation/documentation/iokit/iokit_constants>.

---

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