Start symbol for an compressed kernel

[zhaobin xv]

2013/8/17 Russell King - ARM Linux <linux at arm.linux.org.uk>:
> On Sat, Aug 17, 2013 at 09:56:14PM +0800, zhaobin xv wrote:
>> 2013/8/17 Russell King - ARM Linux <linux at arm.linux.org.uk>:
>> > On Sat, Aug 17, 2013 at 07:39:46PM +0800, zhaobin xv wrote:
>> >> how to find Start symbol for an compressed kernel for arm
>> >
>> > The start address of a compressed kernel is the first byte of the image.
>> >
>> > Symbolically, that is 'start', which is a non-global symbol.  However,
>> > this symbol is useless since it normally is zero, because the entire
>> > image is relocatable and therefore built for address zero.
>> >
>> > However, it is normal to load the image not at address zero.
>>
>> why do U define ENTRY(_start)?
>> Is _start the Start symbol?
>> how to explain _start
>
> There is no _start symbol in the compressed kernel.

But there is ENTRY(_start) and _start in
linux-2.6.22.6\arch\arm\boot\compressed/head.S