On 03/11/15 12:16, Michael Tokarev wrote: > 03.11.2015 11:00, Julio Guerra wrote: >> Ping :) > > Well, I'm not sure what can I do with this. I've no idea what is IBAT to > start > with, so while technically the patch is a one-liner, I've no idea what it does > and how trivial it is :) > > Maybe you can include some context which teaches me what it is all about, and > in > that case it becomes really trivial, or.. I dunno :)
FWIW PPC has a set of IBAT and DBAT registers on chip, each of which indicates a large continuous physical/virtual memory mapping for Instruction and Data memory respectively. The idea is that the OS can use these to provide "fast" virtual to physical lookups instead of invoking a time-consuming hash lookup to provide the translation. >From casual observation comparing with spr_write_ibatu_h() in the same file (which already includes the +4 offset that the patch is adding to spr_read_ibat_h()), it does look like a genuine bug. However it really needs someone who understands PPC architecture a bit more to give a RB to ensure this is doing the right thing. ATB, Mark.
