0001 =====================================
0002 Passing boot parameters to the kernel
0003 =====================================
0004
0005 Boot parameters are represented as a TLV list in the memory. Please see
0006 arch/xtensa/include/asm/bootparam.h for definition of the bp_tag structure and
0007 tag value constants. First entry in the list must have type BP_TAG_FIRST, last
0008 entry must have type BP_TAG_LAST. The address of the first list entry is
0009 passed to the kernel in the register a2. The address type depends on MMU type:
0010
0011 - For configurations without MMU, with region protection or with MPU the
0012 address must be the physical address.
0013 - For configurations with region translarion MMU or with MMUv3 and CONFIG_MMU=n
0014 the address must be a valid address in the current mapping. The kernel will
0015 not change the mapping on its own.
0016 - For configurations with MMUv2 the address must be a virtual address in the
0017 default virtual mapping (0xd0000000..0xffffffff).
0018 - For configurations with MMUv3 and CONFIG_MMU=y the address may be either a
0019 virtual or physical address. In either case it must be within the default
0020 virtual mapping. It is considered physical if it is within the range of
0021 physical addresses covered by the default KSEG mapping (XCHAL_KSEG_PADDR..
0022 XCHAL_KSEG_PADDR + XCHAL_KSEG_SIZE), otherwise it is considered virtual.
