1The chosen node
2---------------
3
4The chosen node does not represent a real device, but serves as a place
5for passing data between firmware and the operating system, like boot
6arguments. Data in the chosen node does not represent the hardware.
7
8
9stdout-path property
10--------------------
11
12Device trees may specify the device to be used for boot console output
13with a stdout-path property under /chosen, as described in ePAPR, e.g.
14
15/ {
16	chosen {
17		stdout-path = "/serial@f00:115200";
18	};
19
20	serial@f00 {
21		compatible = "vendor,some-uart";
22		reg = <0xf00 0x10>;
23	};
24};
25
26If the character ":" is present in the value, this terminates the path.
27The meaning of any characters following the ":" is device-specific, and
28must be specified in the relevant binding documentation.
29
30For UART devices, the preferred binding is a string in the form:
31
32	<baud>{<parity>{<bits>{<flow>}}}
33
34where
35
36	baud	- baud rate in decimal
37	parity	- 'n' (none), 'o', (odd) or 'e' (even)
38	bits	- number of data bits
39	flow	- 'r' (rts)
40
41For example: 115200n8r
42
43Implementation note: Linux will look for the property "linux,stdout-path" or
44on PowerPC "stdout" if "stdout-path" is not found.  However, the
45"linux,stdout-path" and "stdout" properties are deprecated. New platforms
46should only use the "stdout-path" property.
47
48linux,booted-from-kexec
49-----------------------
50
51This property is set (currently only on PowerPC, and only needed on
52book3e) by some versions of kexec-tools to tell the new kernel that it
53is being booted by kexec, as the booting environment may differ (e.g.
54a different secondary CPU release mechanism)
55