Re: [PATCHv3 02/11] arm64: Handle section maps for swapper/idmap

From	"Suzuki K. Poulose" <Suzuki.Poulose@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCHv3 02/11] arm64: Handle section maps for swapper/idmap
Date	2015-10-14 17:10 +0200
Message-ID	<qjvQK-2a2-7@gated-at.bofh.it> (permalink)
References	<qjspQ-5qz-3@gated-at.bofh.it> <qjspQ-5qz-15@gated-at.bofh.it> <qjt2y-6rP-15@gated-at.bofh.it> <qjuhZ-8cu-39@gated-at.bofh.it> <qjvH3-1Iz-3@gated-at.bofh.it>
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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

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Thread

[PATCHv3 02/11] arm64: Handle section maps for swapper/idmap "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-10-14 13:30 +0200
  Re: [PATCHv3 02/11] arm64: Handle section maps for swapper/idmap Mark Rutland <mark.rutland@arm.com> - 2015-10-14 14:10 +0200
    Re: [PATCHv3 02/11] arm64: Handle section maps for swapper/idmap "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-14 15:30 +0200
      Re: [PATCHv3 02/11] arm64: Handle section maps for swapper/idmap Mark Rutland <mark.rutland@arm.com> - 2015-10-14 17:00 +0200
        Re: [PATCHv3 02/11] arm64: Handle section maps for swapper/idmap "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-14 17:10 +0200
          Re: [PATCHv3 02/11] arm64: Handle section maps for swapper/idmap Mark Rutland <mark.rutland@arm.com> - 2015-10-14 17:20 +0200

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