They do respond to requests, albeit quite slowly. I wanted documentation to go with some kernel patches they posted to the linux kernel (IOMMU related), that hinted at a mode I was interested in. It took them two years but the docs showed up a few months ago. I suspect I wasn't the only one asking for more detail about system level (or firmware/hypervisor) features that aren't documented in the instruction arch. I think they understand both at the top and the bottom, that the time for hiding stuff like this is over. Pushing it through the immense bureaucracy still takes time but support from upper mgmt eventually gets it done. The one thing IBM has always been good at is documenting their hardware/software. Somewhere in the late 90's they started to hide much of the lowlevel documentation (like the rest of the industry) but I think the slow realization that doing that doesn't help them (or anyone else) is slowly becoming apparent as the most successful companies are frequently the most open ones (and therefor have better linux/open source support).
LoPAPR http://openpowerfoundation.org/?resource_lib=linux-on-power-... IODA2 http://openpowerfoundation.org/?resource_lib=openpower-io-de...
(although i'm 99% sure the IODA doc is missing a heap of stuff).