ok6410开发板_利用u-boot的printf打印数据

 

   当我们编译u-boot的时候会生成System.map文件，vim System.map，然后查找printf,可以发现printf在u-boot中的运行地址。我们可以利用这个printf打印字符串。

      下面是head.S，text.c和Makefile：

     

       head.S：

abc:
mov ip,sp
stmfd sp!,{fp, ip, lr, pc}
sub fp, ip, #4

bl test

sub sp, fp, #12
ldmfd sp, {fp, sp, pc}

text.c：

void (*show)(char *, ...) = 0x57e10660;

void test(void)
{

    show("i love linux.\n");
}

Makefile：

 

all:
arm-linux-gcc -c head.S test.c
arm-linux-ld -Ttext=0x64000000 -o head.elf led.o test.o
arm-linux-objcopy -O binary head.elf head.bin
cp head.bin /tftpboot
clean:
rm -rf *.elf *.bin *.o

操作方法：

kero > tftp 64000000 head.bin
ERROR: resetting DM9000 -> not responding
dm9000 i/o: 0x18000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 88:88:88:88:88:88
operating at 100M full duplex mode
Using dm9000 device
TFTP from server 192.168.1.100; our IP address is 192.168.1.99
Filename 'led.bin'.
Load address: 0x64000000
Loading: ###
done
Bytes transferred = 32860 (805c hex)
kero > go 64000000
## Starting application at 0x64000000 ...
i love linux.
## Application terminated, rc = 0xE
kero >