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

From	Arnd Bergmann <arnd@arndb.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] arm64: dts: uniphier: change release address of spin-table
Date	2016-04-15 20:50 +0200
Message-ID	<rogYx-7wu-5@gated-at.bofh.it> (permalink)
References	<ro9km-1wo-15@gated-at.bofh.it> <robFv-3uA-3@gated-at.bofh.it> <robPc-3yU-25@gated-at.bofh.it>
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On Friday 15 April 2016 22:13:55 Masahiro Yamada wrote:
> 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.)
> 

Should patch 1 be applied as a bugfix for 4.6 instead?

	Arnd

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

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