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
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