mboot64: example hello world "kernel"

Uses monitor calls to mboot64 to print hello and hang.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: README.

Update readme.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: Add multiboot v1 spec header.

Yup.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: extend lmb to do mem type+tag.

Will be needed to build multiboot memory table.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: LMB integration and ELF work.

- CMD_LMB: Add commands to list memory map/claim/release.

RTSM64 # lmb
    memory.reg[0x0]   = 0x0000000080000000 @ 0x0000000080000000 (MEM0, FREE)
    memory.reg[0x1]   = 0x0000000180000000 @ 0x0000000880000000 (MEM1, FREE)
    reserved.reg[0x0] = 0x0000000000021900 @ 0x0000000080000000 (FRMW, RUNTIME)
    reserved.reg[0x1] = 0x0000000000000001 @ 0x00000000820007a5 (SMLD, BOOT)
    reserved.reg[0x2] = 0x0000000000008000 @ 0x00000000ffff7c00 (MALC, RUNTIME)
RTSM64 # release 0x820007a5 1
RTSM64 # lmb
    memory.reg[0x0]   = 0x0000000080000000 @ 0x0000000080000000 (MEM0, FREE)
    memory.reg[0x1]   = 0x0000000180000000 @ 0x0000000880000000 (MEM1, FREE)
    reserved.reg[0x0] = 0x0000000000021900 @ 0x0000000080000000 (FRMW, RUNTIME)
    reserved.reg[0x1] = 0x0000000000008000 @ 0x00000000ffff7c00 (MALC, RUNTIME)

- ELF: cleanup to use LMB to claim memory
- ELF: nuke vxworks code
- ELF: parse multiboot header if any
- ELF: started writing logic to handle creating mbi
- SEMI: Ensure semiload code claims memory.
- LMB: Change lmb code to disallow overlapping claims.
- Board: make sure stack, env and malloc spaces are described by LMB.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>