[PATCH v3 3/5] arm64: Documentation: clarify Image placement in physical RAM

[Mark Rutland]

Hi Ard,

I take it that this (and patch 4) are superseded by the single-page
idmap approach, and when this is next posted you'll fold the series?

Thanks,
Mark.

On Wed, Mar 18, 2015 at 05:05:06PM +0000, Ard Biesheuvel wrote:
> The early init code maps the kernel image using statically
> allocated page tables. This means that we can only allow
> Image to be placed such that we can map its entire static
> footprint using a single table entry at all but the lowest
> level. So update the documentation to reflect that the Image
> should not cross a 512 MB boundary, which ensures the above
> on both 4k and 64k pages kernels.
> 
> Reviewed-by: Mark Rutland <mark.rutland at arm.com>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
>  Documentation/arm64/booting.txt | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt
> index ab5a90adece3..5949bdbe7aac 100644
> --- a/Documentation/arm64/booting.txt
> +++ b/Documentation/arm64/booting.txt
> @@ -115,8 +115,9 @@ The Image must be placed text_offset bytes from a 2MB aligned base
>  address near the start of usable system RAM and called there. Memory
>  below that base address is currently unusable by Linux, and therefore it
>  is strongly recommended that this location is the start of system RAM.
> -At least image_size bytes from the start of the image must be free for
> -use by the kernel.
> +The physical memory region consisting of image_size bytes counting from
> +the start of the image must be free for use by the kernel, and must not
> +cross a 512 MB physical alignment boundary.
>  
>  Any memory described to the kernel (even that below the 2MB aligned base
>  address) which is not marked as reserved from the kernel e.g. with a
> -- 
> 1.8.3.2
> 
>