From mboxrd@z Thu Jan  1 00:00:00 1970
From: Suzuki.Poulose@arm.com (Suzuki K. Poulose)
Date: Wed, 14 Oct 2015 16:08:43 +0100
Subject: [PATCHv3 02/11] arm64: Handle section maps for swapper/idmap
In-Reply-To: <20151014145158.GA4422@leverpostej>
References: <1444821634-1689-1-git-send-email-suzuki.poulose@arm.com>
 <1444821634-1689-3-git-send-email-suzuki.poulose@arm.com>
 <20151014120618.GB2150@leverpostej> <561E56D4.40506@arm.com>
 <20151014145158.GA4422@leverpostej>
Message-ID: <561E6FFB.3020005@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 14/10/15 15:51, Mark Rutland wrote:
>>>> +/* With 4K pages, we use section maps. */

>> /*
>>   * ARM64 kernel is guaranteed to be loaded at 2M aligned
>>   * address (as per booting requirements). Hence we can use
>>   * section mapping with 4K (section size = 2M) and not with
>>   * 16K(section size = 32M) or 64K (section size = 512M).
>>   */
>
> That sounds much better. I hadn't figured out why myself, so thanks for
> the explanation :)
>
> However, there's one minor nit: the start of memory below the kernel is
> 2M aligned, but the offset means that the kernel itself is not loaded at
> a 2M aligned address.

Oh yes

>
> So how about:
>
> /*
>   * The linear mapping and the start of memory are both 2M aligned (per
>   * the arm64 booting.txt requirements). Hence we can use section mapping
>   * with 4K (section size = 2M) but not with 16K (section size = 32M) or
>   * 64K (section size = 512M).
>   */

Will add this

Thanks
Suzuki