Re: [PATCH 2/2] arm64: dts: uniphier: change release address of spin-table

[Masahiro Yamada]

Hi Mark.

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.)



-- 
Best Regards
Masahiro Yamada