On Friday 15 April 2016 22:13:55 Masahiro Yamada wrote: > 2016-04-15 22:05 GMT+09:00 Mark Rutland <mark.rutland@xxxxxxx>: > > On Fri, Apr 15, 2016 at 07:30:47PM +0900, Masahiro Yamada wrote: > >> The 8-byte register located at 0x59801200 on this SoC is dedicated > >> for waking up secondary CPUs. We can use it and save normal memory. > > > > Generally, it is not safe to use MMIO registers to back spin-table. The > > kernel maps the spin table location with cacheable attributes, so there > > may be speculative accesses to any registes in the same (64K) page, and > > a writeback may be larger than the 8-byte register width (which the > > device might not accept, triggering an SError). > > > > Given that, I do not think this is a good idea. > > I did not know this. Thanks for your advice! > > > Arnd, Olof > > Please drop this patch. > (I think 1/2 is still OK.) > Should patch 1 be applied as a bugfix for 4.6 instead? Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
