Linux 内核启动分析（转）

Linux 内核启动分析（转）
Linux 内核启动分析
1.       内核启动地址
1.1.   名词解释
ZTEXTADDR
解压代码运行的开始地址。没有物理地址和虚拟地址之分，因为此时MMU处于关闭状态。这个地址不一定时RAM的地址，可以是支持读写寻址的flash等存储中介。
Start address of decompressor. here's no point in talking about
virtual or physical addresses here, since the MMU will be off at the
time when you call the decompressor code. You normally call   the
kernel at this address to start it booting. This doesn't have to be
located in RAM, it can be in flash or other read-only or     
read-write addressable medium.
ZRELADDR
       内核启动在RAM中的地址。压缩的内核映像被解压到这个地址，然后执行。
This is the address where the decompressed kernel will be written,
and eventually executed. The following constraint must be valid:
              __virt_to_phys(TEXTADDR) == ZRELADDR
       The initial part of the kernel is carefully coded to be position independent.
TEXTADDR
       内核启动的虚拟地址，与ZRELADDR相对应。一般内核启动的虚拟地址为RAM的第一个bank地址加上0x8000。
       TEXTADDR = PAGE_OFFSET + TEXTOFFST
       Virtual start address of kernel, normally PAGE_OFFSET +
0x8000.This is where the kernel image ends up.  With the latest
kernels, it must be located at 32768 bytes into a 128MB region. 
Previous kernels placed a restriction of 256MB here.
TEXTOFFSET
       内核偏移地址。在arch/arm/makefile中设定。
PHYS_OFFSET
       RAM第一个bank的物理起始地址。
Physical start address of the first bank of RAM.
PAGE_OFFSET
RAM第一个bank的虚拟起始地址。
       Virtual start address of t