chosen.txt 1.3 KB

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  1. The chosen node
  2. ---------------
  3. The chosen node does not represent a real device, but serves as a place
  4. for passing data between firmware and the operating system, like boot
  5. arguments. Data in the chosen node does not represent the hardware.
  6. stdout-path property
  7. --------------------
  8. Device trees may specify the device to be used for boot console output
  9. with a stdout-path property under /chosen, as described in ePAPR, e.g.
  10. / {
  11. chosen {
  12. stdout-path = "/serial@f00:115200";
  13. };
  14. serial@f00 {
  15. compatible = "vendor,some-uart";
  16. reg = <0xf00 0x10>;
  17. };
  18. };
  19. If the character ":" is present in the value, this terminates the path.
  20. The meaning of any characters following the ":" is device-specific, and
  21. must be specified in the relevant binding documentation.
  22. For UART devices, the preferred binding is a string in the form:
  23. <baud>{<parity>{<bits>{<flow>}}}
  24. where
  25. baud - baud rate in decimal
  26. parity - 'n' (none), 'o', (odd) or 'e' (even)
  27. bits - number of data bits
  28. flow - 'r' (rts)
  29. For example: 115200n8r
  30. Implementation note: Linux will look for the property "linux,stdout-path" or
  31. on PowerPC "stdout" if "stdout-path" is not found. However, the
  32. "linux,stdout-path" and "stdout" properties are deprecated. New platforms
  33. should only use the "stdout-path" property.