[PATCH v20 14/14] Documentation: dt: usable-memory and elfcorehdr nodes for arm64 kexec

[Thiago Jung Bauermann]

Hello,

Am Donnerstag, 23 Juni 2016, 17:54:49 schrieb Geoff Levand:
> +linux,usable-memory
> +-------------------
> +
> +This property is set on PowerPC and arm64 by kexec-tools during kdump
> +to tell the crash kernel the base address of its reserved area of memory,
> and +the size. e.g.
> +
> +/ {
> +	chosen {
> +		linux,usable-memory = <0x9 0xf0000000 0x0 0x10000000>;
> +	};
> +};

On powerpc, linux,usable-memory isn't in /chosen. It is put by kexec-tools 
in each /memory node and has the same format as the reg property. During 
early boot, the kernel goes through the /memory nodes to find usable memory 
and for each node, if there's a linux,usable-memory property it will use it 
instead of the reg property to find the ranges of memory it can use (see 
early_init_dt_scan_memory in drivers/of/fdt.c).

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center