[ros-kernel] atapi with bus master dma

[Hartmut Birr]

Hi,

I've started the implementation of bus master dma transfers within
atapi. Currently this is  only implemented for disks. The code is
disabled by default. It could be enabled by defining ENABLE_DMA at the
begin of atapi.c. I've tested the code on two PC's (with building ros on
ros), one with an intel lx chipset (piix) and the other with a promise
Ultra100Tx2 controller. I've found no problem. After this, I was
courageous and have copied atapi.sys to my old NT 4.0 installation. Disk
access works perfect (with and without dma). Cd access doesn't work. It
seems that the 'read TOC' command fails. I've found some entries in the
event log, which currently I doesn't understand. 

- Hartmut