pmoninit

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

			PMON Initialization
			PMON Initialization

Here is a brief description of what happens when PMON
boots (jal is a subroutine call).

Execution starts at 0xbfc00000 (0xa0c00000 on the LR64360). At this 
address there is a jump to _start  (usually at 0xbfc00274).

_start: (pmon/mips.s)
  
  jal cpuInit
	This calls getHostType and then sets up the RAM and returns
	a pointer to the correct cache flush routine, and the CPU
	type.
  jalr s0
	Calls the correct flush routine to flush the Dcache. It calls
	indirect via register s0, which was set by cpuInit.  
	
  jal cpdata
	Copies the .data section from the PROM to the RAM.
  jal clrbss
	Clears the .bss section in RAM.
  jal copyHandler
	Copies the exception handler to the exception vector in RAM.
  jal copyHandler
	Copies the exception handler to the exception vector in RAM.
  jalr s0
	Calls the correct flush routine to flush the Dcache. It calls
	indirect via register s0, which was set by cpuInit.  
	
  jalr s0
	Calls the correct flush routine to flush the Icache. It calls
	indirect via register s0, which was set by cpuInit.  
	
  jal pmoninit
	Calls pmoninit, this is the first piece of C. At this point
	   PMON switches to kseg0 addresses (assuming that PMON was linked
	   at a kseg0 address).
	

pmoninit() (pmon/main.c)
  
  jal mfc0
	Uses mfc0() to read the Status register (C0_SR).
	This is the first time that RAM is assumed to be working.
	If RAM is not working, control will not return from this
	call.
  jal hostInit(8)
	Initialize the DUART. This calls 
	addDevice, which calls the OP_INIT 
	section of the driver.
  jal moninit
	Initializes the core Monitor.
  jal addCmdRec
	Called several times. Adds PMON-specific commands to the Monitor.
	
  jal addEnvRec
	Called several times. Adds PMON-specific environment variables 
	to the Monitor.  
  jal sprintf -- do_cmd
	This pair of functions is called three times. They set two
	environment variables and define the symbol Pmon.
	
  jal addGpRegs 
	Add the Gp registers to the list of registers.
	
  jal hostInit 
	Perform additional initialization.
	
  jal printf 
	Print the first part of the banner.