Re: [PATCH v5 8/8] dt: add documentation of ARM dt boot interface

[Nicolas Pitre]

On Fri, 29 Apr 2011, Grant Likely wrote:

> diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt
> index 50619a0..31d7e8a 100644
> --- a/Documentation/devicetree/booting-without-of.txt
> +++ b/Documentation/devicetree/booting-without-of.txt
[...]
> +1) Entry point for arch/arm
> +---------------------------
> +
> +   There is one single entry point to the kernel, at the start
> +   of the kernel image. That entry point supports two calling
> +   conventions.  A summary of the interface is described here.  A full
> +   description of the boot requirements is documented in
> +   Documentation/arm/Booting
> +
> +        a) ATAGS interface.  Minimal information is passed from firmware
> +        to the kernel with a tagged list of predefined parameters.
> +
> +                r0 : 0
> +
> +                r1 : Machine type number
> +
> +                r2 : Physical address of tagged list in system RAM
> +
> +        b) Entry with a flattened device-tree block.  Firmware loads the
> +        physical address of the flattened device tree block (dtb) into r2,
> +        r1 is not used, but it is considered good practise to use a valid
> +        machine number as described in Documentation/arm/Booting.
> +
> +                r0 : 0
> +
> +                r1 : Valid machine type number.  When using a device tree,
> +                a single machine type number will often be assigned to
> +                represent a class or family of SoCs.
> +
> +                r2 : physical pointer to the device-tree block
> +                (defined in chapter II) in RAM.  Device tree can be located
> +                anywhere in system RAM, but it should be aligned on a 64 bit
> +                boundary.
> +
> +   The kernel will differentiate between ATAGS and device tree booting by
> +   reading the memory pointed to by r1 and looking for either the flattened

s/r1/r2/


Nicolas
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