I have played around with different DMA Buffer Sizes, and I thought to ask about my results.
Currently I would like to use a 32MB-aligned buffer, and by setting the Windows Registry entry for DmaBufferSize to 64MB, I seem consistently able to achieve this. I understand the Driver will only return a 16MB aligned address, but my experience has been the value returned by PCIe7KA_DmaGetBufferSize() is always at least [DmaBufferSize - 16MB], guaranteeing (I think) that I can locate a 32MB-aligned buffer within the allocated kernal space.
My question is, can I count on this to always work the same way? I need to ask, because when I set the Registry value to 256MB, sometimes Windows fails to start the Driver at boot time. That's more than I'll ever need, but it does make it obvious there is a limit. Can you shed a light on what the limit might be? Or at least give me confidence my 32MB-aligned buffer work-around is valid?