Boot option

overview

<code>+--------+----------------+----------------+----------+-----------+
| Boot   | Terminology #1 | Terminology #2 | Actual   | Rockchip  |
| stage  |                |                | program  |  Loader   |
| number |                |                | name     |   Name    |
+--------+----------------+----------------+----------+-----------+
| 1      |  Primary       |  -             | ROM code | BootRom   |
|        |  Program       |                |          |           |
|        |  Loader        |                |          |           |
|        |                |                |          |           |
| 2      |  Secondary     |  1st stage     | u-boot   | MiniLoader|
|        |  Program       |  bootloader    | SPL      |           |
|        |  Loader (SPL)  |                |          |           |
|        |                |                |          |           |
| 3      |  -             |  2nd stage     | U-Boot   |  U-Boot   |
|        |                |  bootloader    |          |           |
|        |                |                |          |           |
| 4      |  -             |  -             | kernel   |  kernel   |
|        |                |                |          |           |
| 5      |  -             |  -             | rootfs   |  rootfs   |
+--------+----------------+----------------+----------+-----------+