要调试裸板，有两种初始化方法，一个是用烧好的uboot初始化，再有就是直接用JLink+GDBServer初始化。代码参考了网上的资料，根据手头的OK6410开发板做了修改。整体代码如下：
# Connect to the J-Link GDBServer
target remote localhost:2331
# Set JTAG speed to 30 kHz
monitor endian little
monitor speed 30
# Reset the target
monitor reset
monitor sleep 10
#
# CPU core initialization
#
# Set the processor to service mode
monitor reg cpsr = 0xd3
# Config MMU
# Flush v3/v4 cache
monitor cp15 7, 7, 0, 0 = 0x0
monitor cp15 8, 7, 0, 0 = 0x0
# Disable MMU stuff and caches
monitor cp15 1, 0, 0, 0 =0x1002
# Peri port setup
monitor cp15 15, 2, 0, 4 = 0x70000013
# Disable watchdog
monitor MemU32 0x7e004000 = 0x00000000
monitor sleep 10
# Disable interrupt
monitor MemU32 0x71200014 = 0xffffffff
monitor MemU32 0x71300014 = 0xffffffff
monitor MemU32 0x7120000C = 0x00000000
monitor MemU32 0x7130000C = 0x00000000
monitor MemU32 0x71200F00 = 0x00000000
monitor MemU32 0x71300F00 = 0x00000000
# Set clock
monitor MemU32 0x7e00f900 = 0x000080de
monitor MemU32 0x7e00f000 = 0x0000ffff
monitor MemU32 0x7e00f004 = 0x0000ffff
monitor MemU32 0x7e00f008 = 0x0000ffff
monitor MemU32 0x7e00f028 = 0x00300000
monitor MemU32 0x7e00f020 = 0x01043310
monitor MemU32 0x7e00f00C = 0x810a0301
monitor MemU32 0x7e00f010 = 0x810a0301
monitor MemU32 0x7e00f014 = 0x80200102
monitor MemU32 0x7e00f018 = 0x00000000
monitor MemU32 0x7e00f01c = 0x00000007
monitor sleep 1
# UART Init
monitor MemU32 0x7f008000 = 0x00220022
monitor memU32 0x7f008020 = 0x00002222
monitor memU32 0x7f005008 = 0x00000000
monitor memU32 0x7f00500c = 0x00000000
monitor memU32 0x7f005000 = 0x00000003
monitor memU32 0x7f005004 = 0x00000e45
monitor memU32 0x7f005028 = 0x00000033
monitor memU32 0x7f00502c = 0x0000dfdd
monitor memU32 0x7f005020 = 0x4f4f4f4f
monitor memU32 0x7f005020 = 0x4b4b4b4b
# Config Mobile DDR SDRAM
monitor MemU32 0x7e00f120 = 0x0000000d
monitor MemU32 0x7e001004 = 0x00000004
monitor MemU32 0x7e001010 = 0x0000040f
monitor MemU32 0x7e001014 = 0x00000006
monitor MemU32 0x7e001018 = 0x00000001
monitor MemU32 0x7e00101c = 0x00000002
monitor MemU32 0x7e001020 = 0x00000006
monitor MemU32 0x7e001024 = 0x0000000a
monitor MemU32 0x7e001028 = 0x0000000c
monitor MemU32 0x7e00102c = 0x0000010b
monitor MemU32 0x7e001030 = 0x0000000c
monitor MemU32 0x7e001034 = 0x00000002
monitor MemU32 0x7e001038 = 0x00000002
monitor MemU32 0x7e00103c = 0x00000002
monitor MemU32 0x7e001040 = 0x00000002
monitor MemU32 0x7e001044 = 0x00000010
monitor MemU32 0x7e001048 = 0x00000010
monitor MemU32 0x7e00100C = 0x0001001a
monitor MemU32 0x7e00104C = 0x00000b45
monitor MemU32 0x7e001200 = 0x000150f0
monitor MemU32 0x7e001304 = 0x00000000
monitor MemU32 0x7e001008 = 0x000c0000
monitor MemU32 0x7e001008 = 0x00000000
monitor MemU32 0x7e001008 = 0x00040000
monitor MemU32 0x7e001008 = 0x00040000
monitor MemU32 0x7e001008 = 0x000a0000
monitor MemU32 0x7e001008 = 0x00080032
monitor MemU32 0x7e001004 = 0x00000000
# Setup GDB for faster downloads
#set remote memory-write-packet-size 1024
set remote memory-write-packet-size 4096
set remote memory-write-packet-size fixed
monitor speed 12000
break start_armboot
load
continue
下载逐行说明：
Monitor reg cpsr = 0xd3
这一行是把cpu置为管理模式，并且设置中断掩码I F T M4 M3 M2 M1 M0，对应于0xd3为0xB11010011， I、F置位设置中断及快速中断掩码， T清位，说明当前为ARM模式下， M置为0xB10011，为管理模式。
monitor MemU32 0x7e004000 = 0x00000000
这一行失能看门狗，该寄存器说明如下：
Watchdog timer [5] 0=Disable, 1=Enable
Clock select [4:3] 00:16 01:32 10:64 11:128
Interrupt generation [2] 0=Disable, 1=EnableReset enable/disable [0]
Monitor MemU32 0x71200014 = 0xFFFFFFFF
Monitor MemU32 0x71300014 = 0xFFFFFFFF
设置VIC0INTENCLEAR及VIC1IntENCLEAR寄存器，该寄存器写0无作用，写1会disable相应的中断：
Clears corresponding bits in the VICINTENABLE Register:0 = no effect1 = interrupt disabled in VICINTENABLE Register.There is one bit of the register for each interrupt source.
网上其它资料都是往里写0，应该是个错误。
Monitor MemU32 0x7120000C = 0x00000000
Monitor MemU32 0x7130000C = 0x00000000
设置所有中断为IRQ，而不是FIQ，该寄存器写0为IRQ，写1为FIQ：
Selects type of interrupt for interrupt request:0 = IRQ interrupt (reset)1 = FIQ interruptThere is one bit of the register for each interrupt source
Monitor MemU32 0x71200F00 = 0x00000000
Monitor MemU32 0x71300F00 = 0x00000000
设置VIC0ADDRERSS及VIC1ADDRESS寄存器，清除当前pending的中断:
Contains the address of the currently active ISR, with reset value0x00000000.A read of this register returns the address of the ISR and sets thecurrent interrupt as being serviced. A read must only be performedwhile there is an active interrupt.A write of any value to this register clears the current interrupt. Awrite must only be performed at the end of an interrupt serviceroutine.
Monitor MemU32 0x7e00f900 = 0x000080de
设置OTHERS寄存器为Synchronous mode，网上资料没有设置sync，要试验一下
Monitor MemU32 0x7e00f000 = 0x0000ffff
Monitor MemU32 0x7e00f004 = 0x0000ffff
Monitor MemU32 0x7e00f008 = 0x0000ffff
设置APLL_LOCK、MPLL_LOCK及EPLL_LOCK寄存器，都设为最大间隔
Monitor MemU32 0x7e00f028 = 0x00300000
设置CLK_DIV2寄存器，主要是设置UART_RATIO:
UART_RATIO [19:16]
UART clock divider ratio
CLKUART = CLKUARTIN / (UART_RATIO + 1)
这里的设置是CLKUART = CLKUARTIN / 4
Monitor MemU32 0x7e00f020 = 0x01043310
设置CLK_DIV0寄存器, 设置的值如下
PCLK_RATIO [15:12] 0x3
HCLKX2_RATIO [11:9] 0x1
HCLK_RATIO [8] 0x1
MPLL_RATIO [4] 0x1
APLL_RATIO [3:0] 0x0
根据如下的计算公式
PCLK = HCLKX2 / (PCLK_RATIO + 1)
HCLKX2 = HCLKX2IN / (HCLKX2_RATIO + 1)
HCLK = HCLKX2 / (HCLK_RATIO + 1)
DOUTMPLL = MOUTMPLL / (MPLL_RATIO + 1)
ARMCLK = DOUTAPLL / (ARM_RATIO + 1)
得到的计算结果
PCLK = HCLKX2 / 4
HCLKX2 = HCLKX2IN / 2
HCLK = HCLKX2 / 2
DOUTMPLL = MOUTMPLL / 2
ARMCLK = DOUTAPLL
Monitor MemU32 0x7e00f00c = 0x810a0301
Monitor MemU32 0x7e00f010 = 0x810a0301
设置APLL_CON及MPLL_CON寄存器，
计算公式为
FOUT = MDIV X FIN / (PDIV X 2SDIV)
对于APLL_CON寄存器：
Enable [31] 0x1
MDIV [25:16] 0x10a(266)
PDIV [13:8] 0x3
SDIV [2:0] 0x1
则FOUT = 266 X 12 / (3 X 2) = 532
对于MPLL_CON寄存器是一样的，也是532
Monitor MemU32 0x7e00f014 = 0x80200102
Monitor MemU32 0x7300f018 = 0x00000000
设置EPLL_CON0寄存器
Enable [31] 0x1
MDIV [23:16] 0x20
PDIV [13:8] 0x1
SDIV [2:0] 0x2
设置EPLL_CON1寄存器
KDIV [15:0] 0x0
根据计算公式：FOUT = (MDIV + KDIV / 216) X FIN / (PDIV X 2SDIV)
可以计算得到FOUT = 32 X 12 / (1 X 4) = 96
Monitor MemU32 0x7e00f01c = 0x00000007
设置CLK_SRC寄存器
UART_SEL [13] 0x0 using MOUT epll
EPLL_SEL [2] 0x1 using FOUT epll
MPLL_SEL [1] 0x1 using FOUT mpll
APLL_SEL [0] 0x1 using FOUT apll
Monitor MemU32 0x7f008000 = 0x00220022
设置GPACON寄存器
GPA0 [3:0] 0x2 UART RXD[0]
GPA1 [7:4] 0x2 UART TXD[0]
GPA2 [11:8] 0x0 Input
GPA3 [15:12] 0x0 Input
GPA4 [19:16] 0x2 UART RXD[1]
GPA5 [23:20] 0x2 UART TXD[1]
Monitor MemU32 0x7f008020 = 0x00002222
设置GPBCON寄存器
GPB0 UART_RXD[2]
GPB1 UART TXD[2]
GPB2 UART RXD[3]
GPB3 UART TXD[3]
Monitor memU32 0x7f005008 = 0x00000000
设置UFCON0寄存器：
FIFO disable
Monitor memU32 0x7f00500c = 0x00000000
设置UMCON0寄存器：
Modem interrupt Disable
Monitor MemU32 0x7f005000 = 0x00000003
设置ULCON0寄存器
Word Length 8-bit
One shop bit per frame
No parity Mode Normal mode operation
Monitor MemU32 0x7f005004 = 0x00000e45
设置UCON0寄存器
Clock selection EXT_UCLK1: DIV_VAL=(EXT_UCLK1/(bps x16))-1
Tx Interrupt Type: Level
Rx Interrupt Type: Pulse
Rx Time Out Enable: disable
Rx Error status interrupt enable: enable