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SPARTAN kernel currently supports emulated MIPS R4000 32-bit
little-endian architecture. In other words, it can only run in MIPS
R4000 emulator called msim. This emulator is being developed by Viliam
Holub:

http://nenya.ms.mff.cuni.cz/~holub/msim

Note that msim diverges from real MIPS hardware in some aspects.
Therefore, some non-trivial changes will be necessary for a real
hardware port. The simulator is described in this manual:

http://nenya.ms.mff.cuni.cz/~holub/msim/msim.ps

You'll need a msim.conf script like this:

    #
    # MSIM configuration script
    #

    add dcpu mips1

    add rwm     mainmem     0               16M load "kernel.bin"
    add rom     startmem        0x1fc00000  1k      load "load.bin"

    add dprinter    printer         0xA000000



BOOTSTRAP
=========
Because the mips port uses binary executable format and for some other
architectural reasons, it shares one address for bootstrap entry
(address where control is passed from loader) and for TLB refill
exception entry. The former is used only once during system bootstrap.
From that point further, only TLB refill exception entry uses that
address. Note that this is the reason why main_bsp() is called from
tlb_refill() code.