The boot loader must create and initialise the kernel tagged list.
A valid tagged list starts with ATAG_CORE and ends with ATAG_NONE.
The ATAG_CORE tag may or may not be empty.  An empty ATAG_CORE tag
has the size field set to '2' (0x00000002).  The ATAG_NONE must set
the size field to zero.

Any number of tags can be placed in the list.  It is undefined
whether a repeated tag appends to the information carried by the
previous tag, or whether it replaces the information in its
entirety; some tags behave as the former, others the latter.

The boot loader must pass at a minimum the size and location of
the system memory, and root filesystem location.  Therefore, the
minimum tagged list should look:

        +-----------+
base -> | ATAG_CORE |  |
        +-----------+  |
        | ATAG_MEM  |  | increasing address
        +-----------+  |
        | ATAG_NONE |  |
        +-----------+  v

The tagged list should be stored in system RAM.