Linux kernel question

[=?gb2312?q?do=20do?= <flygong@yahoo.com>]

Hello croutons:
	I'm a chinese student reading linux
2.0.34 version source code .I meet some question.Mybe
you can help me.My questions :the first,what does the
linux 
memory layout look like?the second question:there a
line
"memory_start = (unsigned long) &_end;"in function of
void setup_arch in linux/arch/i386/kernel/setup.c,what
is 
"_end"? And could you tell me where to find document
aout
these question?
	Thank you !
			you honest friend  gong 99/12/22

	My e_mail:flygong@yahoo.com



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