VDMAD_Reserve_Buffer_Space

The VDMAD_Reserve_Buffer_Space service allows other devices that are going to handle DMA to make sure that VDMAD allocates a buffer large enough for any transfers that they might require. It also allows a device to specify a maximum physical address that would be valid for the device's DMA requests (such as 1M for an XT.) During the Init_Complete phase of initialization, VDMAD allocates the DMA buffer using all of the constraints specified by other devices. For example, the buffer is at least as big as the largest size specified by the calls to this service, and it allocates below the lowest maximum physical addresses specified.

This service is only available before the Init_Complete message.

Parameters

EAX

Specifies the number of pages requested.

ECX

Specifies the maximum physical address that can be included in a DMA transfer. If this parameter is zero, there is no limit.

Return Value

This service has no return value.

Uses

Flags