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include vdmad.inc
 
VxDcall 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 1Mb 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.
 
Parameter  Description
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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
 
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