关于天嵌提供的U-BOOT-1.1.6
最近在学习UBOOT，自已也已成功移植了UBOOT1.1.6版本，但跟天嵌提供的UBOOT1.1.6版本相比，不能引导未加头信息的内核(zImage)，于是看了天嵌的UBOOT，详细如下：1、定义了“boot_zImage”这个命令，命令的函数在lib_arm/boot_zImage.c中实现；
2、执行“boot_zImage”命令时调用do_boot_zImage()， do_boot_zImage()调用boot_zImage(0x200000,0x300000)（传入的参数意义是：0x200000是内核映像文件在NAND的偏移地址，0x300000是内核映像文件的SIZE）；
3、在boot_zImage()函数中实现了从NAND拷贝到SDRAM、设置机器ID、设置启动参数等并最终调用call_linux(0, mach_type, to)，跳转到内核入口处执行了。
代码如下：
int boot_zImage(ulong from, size_t size)
{
int ret;
ulong boot_mem_base; /* base address of bootable memory */
ulong to;
ulong mach_type;
boot_mem_base = 0x30000000;
/* copy kerne image */
to = boot_mem_base + LINUX_KERNEL_OFFSET;//内核入口地址 = 0x30008000
printf("Copy linux kernel from 0x%08lx to 0x%08lx, size = 0x%08lx ... ",
from, to, size);
ret = copy_kernel_img(to, (char *)from, size);//从NAND的0x200000处读0x300000大小的内核到0x30008000处
if (ret) {
printf("failed\n");
return -1;
} else {
printf("Copy Kernel to SDRAM done,");
}
if (*(ulong *)(to + 9*4) != LINUX_ZIMAGE_MAGIC) {
printf("Warning: this binary is not compressed linux kernel image\n");
printf("zImage magic = 0x%08lx\n", *(ulong *)(to + 9*4));
} else {
//printf("zImage magic = 0x%08lx\n", *(ulong *)(to + 9*4));
;
}
/* Setup linux parameters and linux command line */
setup_linux_param(boot_mem_base + LINUX_PARAM_OFFSET);//0x30000100,设置内存、命令行参数等
/* Get machine type */
mach_type = MACH_TYPE_S3C2440;//机器ID
// printf("MACH_TYPE = %d\n", mach_type);
/* Go Go Go */
printf("NOW, Booting Linux......\n");
call_linux(0, mach_type, to);//启动内核
return 0;
}
//启动内核 r0 = 0,r1 = ID,r2 = 0x30008000
voidcall_linux(long a0, long a1, long a2)
{
local_irq_disable();
cache_clean_invalidate();
tlb_invalidate();
__asm__(
"mov r0, %0\n"
"mov r1, %1\n"
"mov r2, %2\n"
"mov ip, #0\n"
"mcr p15, 0, ip, c13, c0, 0\n" /* zero PID */
"mcr p15, 0, ip, c7, c7, 0\n" /* invalidate I,D caches */
"mcr p15, 0, ip, c7, c10, 4\n" /* drain write buffer */
"mcr p15, 0, ip, c8, c7, 0\n" /* invalidate I,D TLBs */
"mrc p15, 0, ip, c1, c0, 0\n" /* get control register */
"bic ip, ip, #0x0001\n"/* disable MMU */
"mcr p15, 0, ip, c1, c0, 0\n" /* write control register */
"mov pc, r2\n"//pc = 0x30008000，跳到内核处执行
"nop\n"
"nop\n"
: /* no outpus */
: "r" (a0), "r" (a1), "r" (a2)
: "r0","r1","r2","ip"
);
疑问：以上“r2”为什么是内核的入口地址而不是参数的地址，因为还未学习内核，所以不懂。难道这就是zImage和uImage的区别？{:2_30:}
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