[$] DMA addresses for UIO

The UserspaceI/O (UIO) subsystem was first added to the kernel byHans J. Koch for the 2.6.32 release in 2007. Its purpose is to facilitatethe writing of drivers (mostly) in user space; to that end, it providesaccess to a number of resources that user-space code normally cannot touch.One piece that is missing, though, is DMA addresses. A proposal tofill that gap from Bastien Curutchet is running into some opposition,though.