mini2440 uart 疑惑

code:

复制代码 int serial_init(void) {     volatile struct mini2440_uart *uart = (volatile struct mini2440_uart *)MINI2440_UART0_BASE;     unsigned long reg = 0, pclk;     /* FIFO enable, Tx/Rx FIFO clear */     uart->ufcon = 0x07;     uart->umcon = 0x0;          /* Normal,No parity,1 stop,8 bit */     uart->ulcon = 0x03;     /*      * tx=level,rx=edge,disable timeout int.,enable rx error int.,      * normal,interrupt or polling      */     uart->ucon = 0x0245;     pclk = get_pclk();     /* value is calculated so : (int)(PCLK/(16*baudrate)) -1 */     reg = (int)(pclk / (16*BAUDRATE)) - 1;     uart->ubrdiv = reg;     pll_delay(100);     PUTC('H');     PUTC('e');     PUTC('l');     PUTC('l');     PUTC('o');     PUTC('\r');     PUTC('\n');     PUTS("serial init ok\r\n");     PUTC('W');     PUTC('o');     PUTC('r');     PUTC('l');     PUTC('d');     PUTC('\r');     PUTC('\n');     return (0); } void PUTC(char c) {     volatile struct mini2440_uart *uart = (volatile struct mini2440_uart *)MINI2440_UART0_BASE;     while (uart->ufstat & 0x400)         ;     uart->utxh = c; } void PUTS(const char *s) {     while (*s) {         PUTC(*s);         s++;     }     }

串口输出：
Hello
s 䁃�\ ��P 埃�� ��X 堃� ��` 傃�World

上面的PUTS函数看起来没什么问题，为什么却无法正确输出呢？

我发现这是程序无法正确访问 字符串常量 所致。

复制代码 2f4:    e59fc0f8     ldr    ip, [pc, #248]    ; 3f4 <serial_init+0x214> 2f8:    e5c23020     strb    r3, [r2, #32] 2fc:    e3a01073     mov    r1, #115    ; 0x73 300:    e5923018     ldr    r3, [r2, #24] 304:    e3130b01     tst    r3, #1024    ; 0x400 308:    1afffffc     bne    300 <serial_init+0x120> 30c:    e5c21020     strb    r1, [r2, #32] 310:    e5fc1001     ldrb    r1, [ip, #1]! 314:    e3510000     cmp    r1, #0 318:    1afffff8     bne    300 <serial_init+0x120> 3f4:    00000444     andeq    r0, r0, r4, asr #8 00000444 <.rodata>: 444:    69726573     ldmdbvs    r2!, {r0, r1, r4, r5, r6, r8, sl, sp, lr}^ 448:    69206c61     stmdbvs    r0!, {r0, r5, r6, sl, fp, sp, lr} 44c:    2074696e     rsbscs    r6, r4, lr, ror #18 450:    0a0d6b6f     beq    35b214 <PUTS+0x35ae00> 454:    00000000     andeq    r0, r0, r0

上面是dump elf 文件得出的。为什么呢？

原来是链接地址搞错了！