From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm: fix flush_pfn_alias
Date: Mon, 20 Oct 2014 14:47:08 +0100 [thread overview]
Message-ID: <20141020134708.GU27405@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <2144086.KBLsLT82pe@wuerfel>
On Mon, Oct 20, 2014 at 03:39:44PM +0200, Arnd Bergmann wrote:
> On Monday 20 October 2014 21:54:02 Jungseung Lee wrote:
> > L1_CACHE_BYTES could be larger than real L1 cache line size.
> > In that case, flush_pfn_alias function would omit to flush last bytes
> > as much as L1_CACHE_BYTES - real cache line size.
>
> Can you list an example on what CPU this would happen in the
> patch description? Isn't the L1 cache line size always 32 bytes on ARM?
No, there are 64-byte cache lines in some v7 CPUs.
> Is this needed in stable backports?
The MCRR instruction is deprecated (presumably because, as I discovered
in the early days, it can prevent the system making progress under high
interrupt load), but is only used on ARMv6 CPUs with aliasing cachces -
which have a cache line size of 32. However, when built alongside ARMv7,
it is possible that L1_CACHE_SIZE could be 64.
The patch seems sane on the face of it.
--
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2014-10-20 13:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-20 12:54 [PATCH] arm: fix flush_pfn_alias Jungseung Lee
2014-10-20 13:39 ` Arnd Bergmann
2014-10-20 13:43 ` Will Deacon
2014-10-20 13:47 ` Russell King - ARM Linux [this message]
2014-10-20 15:54 ` Jungseung Lee
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