ppc vs. powerpc status update, please

What's the _current_ trend with those 2 archs, specifically,respecting 
embedded boards, the make ARCH=powerpc ***_defconfig for a board under ppc 
"just should work" doesn't seem to hold and I didn't find any provisions 
for that. (I read in an earlier post it "should"). Are ppc platforms still 
supposed to migrate to under powerpc? I am not quite clear where to put 
all board-specific stuff then, in that post it was told "you almost don't 
need anything, just use device tree and a correct CPU support, and put 
your specific _drivers_ somewhere". How is it in reality?

Thanks
Guennadi
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Guennadi Liakhovetski