Hi Arnd, 2016-04-16 3:48 GMT+09:00 Arnd Bergmann <arnd@xxxxxxxx>: > 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? > Yes, please! -- Best Regards Masahiro Yamada -- 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
