Hello to all dma specialists
I set up a DMA read and write transfer to and from a PCI card. The PCI
card is busmaster capable but not scatter/gather. I actually can do dma
read and write transfers but have problem freeing the map registers and
adapter channels. Basically I saw there are two commands to do this:
a) FreeMapRegisters()
and
b) FreeAdapterChannel()
according to the “Walter Oney” book with a) only the map registers are
released while with b) both the adapter object and the map registers
will be released. Do I understand that correctly so far?
First I tried just with b) to release the adapter objects after the
whole dma transfer was finished. It worked in the first few transfers,
but after a few more transfers, the adaptercontrol routine (provided
from my driver) was not called anymore from the system and I suspected
that there are no more dma resources. I had to restart the system again
and voilà I could to dma again, for a while…
I added a) before b) and now the driver verifier complains:
“Driver has freed too many simultaneous adapter channels”
the next thing what I see is a blue screen…
Can somebody help me?
Thx
Daniel