I know the canonical answer to this is "write a full-on device driver". I need to write two registers in the DCR on a Virtex5 PPC440; just two, not a big pile, not a complex operation, not lots of exciting and dynamic chains of events. Just write two registers. mtdcr, times two.
Of course, I can't seem to do this in a program running under Linux, as it is a privileged instruction.
I've gone through AppNote 1129, and the odds that I'll screw something up trying to integrate the pieces of that that I actually need, are way beyond my simple need to write two registers. So I'm looking to the oracles on this forum for another way 'round: can the DCR space be memory-mapped? Is there a system call to touch DCRs? What's the most straightforward way to write two DCR registers?