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

[Suzuki K. Poulose]

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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