From mboxrd@z Thu Jan  1 00:00:00 1970
From: steve.capper@linaro.org (Steve Capper)
Date: Fri, 2 May 2014 10:11:36 +0100
Subject: [PATCH] arm64: mm: Create gigabyte kernel logical mappings where
 possible
In-Reply-To: <000801cf65a2$44551e10$ccff5a30$@samsung.com>
References: <1398857782-1525-1-git-send-email-steve.capper@linaro.org>
 <000801cf65a2$44551e10$ccff5a30$@samsung.com>
Message-ID: <20140502091135.GA30999@linaro.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Fri, May 02, 2014 at 10:03:02AM +0900, Jungseok Lee wrote:
> On Wednesday, April 30, 2014 8:36 PM, Steve Capper wrote:
> > We have the capability to map 1GB level 1 blocks when using a 4K granule.
> > 
> > This patch adjusts the create_mapping logic s.t. when mapping physical memory on boot, we attempt to
> > use a 1GB block if both the VA and PA start and end are 1GB aligned. This both reduces the levels of
> > lookup required to resolve a kernel logical address, as well as reduces TLB pressure on cores that
> > support 1GB TLB entries.
> > 
> > Signed-off-by: Steve Capper <steve.capper@linaro.org>
> > ---
> > Hello,
> > This patch has been tested on the FastModel for 4K and 64K pages.
> > Also, this has been tested with Jungseok's 4 level patch.
> > 
> > I put in the explicit check for PAGE_SHIFT, as I am anticipating a three level 64KB configuration at
> > some point.
> > 
> > With two level 64K, a PUD is equivalent to a PMD which is equivalent to a PGD, and these are all level
> > 2 descriptors.
> > 
> > Under three level 64K, a PUD would be equivalent to a PGD which would be a level 1 descriptor thus may
> > not be a block.
> > 
> > Comments/critique/testers welcome.
> 
> Hi, Steve
> 
> I've tested on my platform, and it works well.
> 

Thanks for giving this a go!

> If SoC design follows "Principles of ARM Memory Maps",
> PA should be supposed to be 1GB aligned. Thus, I think
> this patch is effective against them.
> 
> Best Regards
> Jungseok Lee
>