PROBLEM: My 'memoryDesc-> writeBytes' call seems to be working in that the returned value is as expected but the data that gets returned to the Userspace client is not changed. ================================================ PARTICULARS: My driver is overriding a Type05 device READ_CD function. After the super::READ_CD(...); call returns, I take a look at the buffer and, under special circumstances, may decide to change some of the data in the buffer. I call memoryDesc->prepare(kIODirectionOutIn); For purposes of checking on and confirming the map status, A memoryDesc->map(0) call is made (to get the IOMemoryMap*) and then a call to getMapOptions returns kIOMapAnywhere. Call bytesWritten = memoryDesc->writeBytes(myOffset, myBuffer, byteCount); Observe that bytesWritten == byteCount; It looks like all went well. Any ideas why the data arrives back in Userspace with no apparent change? Thanks for any input or suggestions, Lance Drake _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.