linux-kernel - RE: [Q] L1_CACHE_BYTES on flush_pfn

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Date:	Sun, 26 Jan 2014 14:13:43 +0900
From:	Jungseung Lee <js07.lee@...sung.com>
To:	'Catalin Marinas' <catalin.marinas@....com>
Cc:	linux-arm-kernel@...ts.infradead.org, linux@....linux.org.uk,
	linux-kernel@...r.kernel.org
Subject: RE: [Q] L1_CACHE_BYTES on flush_pfn_alias function.

Not to flush some more bytes. In the scenario, they can *omit* to flush last 32 bytes.

L1_CACHE_BYTES = 64 (ARM v7, CA9)

asm(    "mcrr   p15, 0, %1, %0, c14\n"
    "   mcr p15, 0, %2, c7, c10, 4"
        :
        : "r" (to), "r" (to + PAGE_SIZE - L1_CACHE_BYTES), "r" (zero)
        : "cc");
-----Original Message-----
From: Catalin Marinas [mailto:catalin.marinas@....com] 
Sent: Saturday, January 25, 2014 12:43 AM
Cc: linux-arm-kernel@...ts.infradead.org; linux@....linux.org.uk; linux-kernel@...r.kernel.org
Subject: Re: [Q] L1_CACHE_BYTES on flush_pfn_alias function.

On Fri, Jan 17, 2014 at 09:54:42AM +0000,        wrote:
> Follow the mailing-list
> http://comments.gmane.org/gmane.linux.ports.arm.omap/31686
> 
> >>Setting the L1 cache line size larger than it actually is should be safe.
> 
> the written code expected as L1_CACHE_BYTES should be real cache line 
> size has bug.
> It looks like that flush_pfn_alias function should be fixed.

Did you actually notice any problem with flushing some more bytes? It's a clean+invalidate rather than invalidate, I don't see any problem.

--
Catalin

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