ID Number: Q77998
3.00
WINDOWS
Summary:
The Virtual DMA Services (VDS) provide application programs that use
DMA (direct memory access) with greater control over how the DMA
hardware is virtualized. However, there are several errors in VDS
support when Windows 3.0 is running in enhanced mode. The following
list should help programmers to avoid these errors while still making
use of VDS functions.
More Information:
The following list summarizes the affected functions and describes
errors that may occur when they are used:
Lock DMA Region, AX = 8103h
---------------------------
- The automatic remap and copy features do not function correctly and
should not be used.
- If an error occurs during the execution of this function, the error
code does not correctly indicate the cause of the error.
Unlock DMA Region, AX = 8104h
-----------------------------
- If an error occurs during the execution of this function, the error
code does not correctly indicate the cause of the error.
Lock/Unlock DMA Region
----------------------
- No validation is done on the OFFSET field to verify that the
specified region is not greater than the segment length.
Scatter/Gather Lock Region, AX = 8105h
--------------------------------------
- This function may incorrectly return zero instead of the resultant
physical page address for pages that were originally not present.
Release DMA Buffer, AX = 8108h
------------------------------
- This function works correctly only when "copy" is specified.
Copy Into DMA Buffer, AX = 8109h
--------------------------------
- The copy count is not correctly interpreted in this function.
Copy Out Of DMA Buffer, AX = 810Ah
----------------------------------
- The copy count is not correctly interpreted in this function.
Additional reference words: VDS