Re: [PATCH v8 5/5] dt-bindings: chosen: Document linux,low-memory-range for arm64 kdump

[Rob Herring]

On Thu, May 21, 2020 at 3:35 AM Chen Zhou <chenzhou10@xxxxxxxxxx> wrote:
>
> Add documentation for DT property used by arm64 kdump:
> linux,low-memory-range.
> "linux,low-memory-range" is an another memory region used for crash
> dump kernel devices.
>
> Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx>
> ---
>  Documentation/devicetree/bindings/chosen.txt | 25 ++++++++++++++++++++
>  1 file changed, 25 insertions(+)

chosen is now a schema documented here[1].

> diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
> index 45e79172a646..bfe6fb6976e6 100644
> --- a/Documentation/devicetree/bindings/chosen.txt
> +++ b/Documentation/devicetree/bindings/chosen.txt
> @@ -103,6 +103,31 @@ While this property does not represent a real hardware, the address
>  and the size are expressed in #address-cells and #size-cells,
>  respectively, of the root node.
>
> +linux,low-memory-range
> +----------------------
> +This property (arm64 only) holds a base address and size, describing a
> +limited region below 4G. Similar to "linux,usable-memory-range", it is
> +an another memory range which may be considered available for use by the
> +kernel.

Why can't you just add a range to "linux,usable-memory-range"? It
shouldn't be hard to figure out which part is below 4G.

Rob

[1] https://github.com/devicetree-org/dt-schema/blob/master/schemas/chosen.yaml