Re: cPCI shared memory driver

The Other Roger wrote: 
Thanks.  Let me add that we have a lot of experience in these kinds of issues
for non-Windows systems so one of the things I need to know is where do I find
Windows documentation for issues such as locking down physical memory for other
devices on the bus to access but still enabling the local apps access to this
memory symbolically?  Also is all the needed information for writing drivers in
the DDK (we've written a zillion drivers but not Windows drivers) or is there
better documentation in books, etc.?

Roger

Gary G. Little wrote:

Damn I hate when I do that. :(

I've used fibre channel at 1.2 Gbps using remote DMA to do some what the
same thing. I did not have the number of perepherals you mention but given
that you have locked down the memory properly and have solid handshaking to
enusre memory is being accessed by only one processor, you should be able to
do this. In my situation I did not have to worry about cache, because I had
two FC cards pluggedinto each other on two seperate systems who were in no
way sharing the same bus.

The ddk docs are fairly complete, but difficult to understand if you don't know what they are talking about to begin with. Walter Oney's Programming the Windows Driver Model (2ed, Microsoft Press) is considered to be essential as a supplement to the DDK.

The OS provides mechanisms to lock virtual-physical memory mappings explicitly for device access. The x86 hardware and chipsets guarantee cache coherency for all memory access for both peripheral devices and host processors.

It is unclear exactly what you mean by 'lock down physical memory for other devices on the bus to access ...'. If you mean something more than the above mentioned virtual-physical mapping lock down, then no any other synchronization mechanism is algorithmic, although the OS of course provides a whole range of synchronization constructs for use within the OS programming environment.

--

=====================
Mark Roddy DDK MVP
Windows 2003/XP/2000 Consulting
Hollis Technology Solutions 603-321-1032
www.hollistech.com
.

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