Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1379808

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

Show all headers | View raw

Hi Mark.

2016-04-15 22:05 GMT+09:00 Mark Rutland <mark.rutland@arm.com>:
> 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

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 2/2] arm64: dts: uniphier: change release address of spin-table Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-04-15 12:40 +0200
  Re: [PATCH 2/2] arm64: dts: uniphier: change release address of  spin-table Mark Rutland <mark.rutland@arm.com> - 2016-04-15 15:10 +0200
    Re: [PATCH 2/2] arm64: dts: uniphier: change release address of spin-table Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-04-15 15:20 +0200
      Re: [PATCH 2/2] arm64: dts: uniphier: change release address of spin-table Arnd Bergmann <arnd@arndb.de> - 2016-04-15 20:50 +0200
        Re: [PATCH 2/2] arm64: dts: uniphier: change release address of spin-table Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-04-16 16:50 +0200

csiph-web