linux内核启动地址,ARM linux内核启动时几个关键地址

.word      user_stack+4096           @ sp

上面这段代码得到内核代码的入口地址，保存在r4中。

/*

* Check to see if we will overwrite ourselves.

*   r4 = final kernel address

*   r5 = start of this image

*   r2 = end of malloc space (and therefore this image)

* We basically want:

*   r4 >= r2 -> OK

*   r4 + image length <= r5 -> OK

*/

cmp r4, r2

bhs wont_overwrite

add r0, r4, #4096*1024 @ 4MB largest kernel size

cmp r0, r5

bls   wont_overwrite

mov r5, r2                    @ decompress after malloc space

mov r0, r5

mov r3, r7

bl     decompress_kernel

b     call_kernel

上面代码判断解压后的内核代码会不会覆盖原来的内核映像，然后调用内核解压缩函数decompress_kernel()。

ulg

decompress_kernel(ulg output_start, ulg free_mem_ptr_p, ulg free_mem_ptr_end_p,

int arch_id)

{

output_data            = (uch *)output_start;    /* 指定内核执行地址，保存在r4中*/

free_mem_ptr        = free_mem_ptr_p;

free_mem_ptr_end = free_mem_ptr_end_p;

__machine_arch_type    = arch_id;

arch_decomp_setup(); /*解压缩前的初始化和设置，包括串口波特率设置等*/

makecrc();           /*CRC校验*/

putstr("Uncompressing Linux...");

gunzip();            /*调用解压缩函数*/

putstr(" done, booting the kernel.n");

return output_ptr;

}

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