On Mon, Jun 27, 2022 at 11:21 PM Jason A. Donenfeld <Jason@xxxxxxxxx> wrote:
>
> Document the /chosen/rng-seed property, which has existed for quite some
> time but without an entry in this file.
>
> Fixes: 428826f5358c ("fdt: add support for rng-seed")
> Cc: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Rob Herring <robh@xxxxxxxxxx>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> ---
It's currently documented in
https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/chosen.yaml
https://lore.kernel.org/lkml/CAL_Jsq+uSdk9YNbUW35yjN3q8-3FDobrxHmBpy=4RKmCfnB0KQ@xxxxxxxxxxxxxx/
> Documentation/devicetree/bindings/chosen.txt | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
> index 1cc3aa10dcb1..49b175e133b2 100644
> --- a/Documentation/devicetree/bindings/chosen.txt
> +++ b/Documentation/devicetree/bindings/chosen.txt
> @@ -7,6 +7,21 @@ arguments. Data in the chosen node does not represent the hardware.
>
> The following properties are recognized:
>
> +rng-seed
> +--------
> +
> +This property is used to initialize the kernel's random number generator at
> +the earliest possible opportunity, and will be credited if CONFIG_RANDOM_
> +TRUST_BOOTLOADER is set. All hardware that has an opportunity to set this
> +with high quality randomness is encouraged to do so. It is parsed as a byte
> +array, which should be at least 32 bytes long:
> +
> +/ {
> + chosen {
> + rng-seed = <... random bytes ...>;
> + };
> +};
> +
>
> kaslr-seed
> -----------
> --
> 2.35.1
>
