From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCH v2 10/11] PM / Hibernate: clean cached pages on architectures that require it
Date: Sat, 14 Nov 2015 00:38:50 +0100
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To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: James Morse <james.morse@arm.com>, Pavel Machek <pavel@ucw.cz>, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, Will Deacon <will.deacon@arm.com>, Sudeep Holla <sudeep.holla@arm.com>, Kevin Kang <kkang@intrinsyc.com>, Geoff Levand <geoff@infradead.org>, Catalin Marinas <catalin.marinas@arm.com>, Mark Rutland <mark.rutland@arm.com>, AKASHI Takahiro <takahiro.akashi@linaro.org>, wangfei <w.f@huawei.com>, Marc Zyngier <marc.zyngier@arm.com>

On Thursday, November 12, 2015 11:47:05 AM Lorenzo Pieralisi wrote:
> On Thu, Nov 12, 2015 at 01:48:32AM +0100, Rafael J. Wysocki wrote:
> > On Wednesday, November 11, 2015 11:40:39 AM Lorenzo Pieralisi wrote:
> > > Hi Pavel, Rafael,
> > > 
> > > Do you have any feedback on this patch ?
> > > 
> > > It is fundamental to this series and affects Hibernate core code so if you
> > > have any feedback that would be much appreciated.
> > 
> > I'm really not familiar with the flush_icache_range() interface.
> > 
> > What exactly does it do?
> 
> It is used to sync a memory range that is written into (eg loading
> modules, copying from snapshot is basically the same thing, reads from
> storage and restore pages that might well be executable code), in particular
> to sync the I-cache and the D-cache, eg on arm64 the page that the snapshot
> code is copying might be executable code that has to be cleaned from the
> D-cache so that it is made visible to the I-cache.
> 
> On x86 it is a NOP AFAIK.

If that's the case, I have no problems with this change as long as the code
works on architectures with non-trivial flush_icache_range().

Thanks,
Rafael