[PATCH 2/2] arm64: dts: uniphier: change release address of spin-table
arnd at arndb.de
Fri Apr 15 11:48:05 PDT 2016
On Friday 15 April 2016 22:13:55 Masahiro Yamada wrote:
> 2016-04-15 22:05 GMT+09:00 Mark Rutland <mark.rutland at 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?
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