[Xen-devel] Questions about memory zone

[ruby young <yangyang@xxxxxxxxxxxxxxx>]

Hi, all~

I'm interested in memory of xen. And I wondered what does the real mean of xen 'zone'. It seems different from linux 'zone'.

In the source code of xen-3.3.0/xen/common/page_alloc.c, there is defined:

#define pfn_dom_zone_type(_pfn) (fls(_pfn)-1)

 

and NR_ZONES is defined:

#define NR_ZONES (PADDR_BITS - PAGE_SHIFT)

 

It seems Zone in xen set up as physic address and are separate by the last pfn bit set.

But Why does Xen Zone organize like this? And What does the Zone mean?

 

Best Wishes!

 

                                                                                    Ruby Young

-- 
Best wishes

杨漾
北京航空航天大学计算机学院体系结构研究所
电话:010-82338059-132
邮件:9907yruby@xxxxxxxxx
地址：北京市海淀区学院路37号北京航空航天大学新主楼 G座1026
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Yang Yang
Institute of Computer Architecture and System 
BeiHang University（BUAA）
Tel: (86-10)82338059-132
Email: 9907yruby@xxxxxxxxx
Addr: Room 1026,Building G,The New Main Building,37# Xueyuan Rd.,Haidian District, Beijing 100083, PRC
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