The ioat(4) driver can only be accessed from kernelspace, so it should probably be moved to section 9. Also, the cross-referenced program ioatcontrol(8) is a dead link. That program doesn't get installed and neither does its man page. ioat(4) should probably just refer to its source location instead: tools/tools/dev/ioat/ioatcontrol.
I'm not sure about the section 9 claim. Is there precedent one way or the other?
As far as ioatcontrol(8): yeah, I agree that should be fixed — there's no reason that program should live outside of tools/ or tests/.
Btw, it looks like xdma(4) (undocumented entirely, of course) is the start of a generic DMA engine interface ioat(4) might implement. Unfortunately, last time I looked the interface wasn't general enough for ioat.
I guess there is precedent for leaving it in section 4. ciss(4) and cpufreq(4) both have similar API documentation in section 4.