Hello, nouveau still does not support 64k pages, so I believe this bug is still current.
It may not be the only one active on PPC64BE though: having built a vanilla 4.11.5 using debian's 4.11 config and changing to 4k pages is sadly not enough to make X work on a Powermac G5 ("late 2005" model) with NV47. The most visible aspect of the issue is similar in both 64k and 4k pages: after a cold boot, there is a narrow solid grey rectangle from screen top-left corner along top border which width seems to depend on page size, and under it random noise in large vertical rectangles with varying dominant hue (mostly white, mostly black, mostly cyan and mostly magenta). After a warm reboot from OSX, elements of its GUI are visible instead of these hue, with the same amount of random noise added over it. The dynamic effects are that once X has been started, chvt blocks (so there is no going back to text mode), and X takes a long while to die (several minutes) which also affects reboots and shutdown (maybe systemd reaching its timeout threshold ?). ssh works fine during that time. Regards, -- Vincent Pelletier