PCDVD數位科技討論區 - 瀏覽單個文章 - 沒想到DDR3 8G的時代這麼快就到了

引用:

作者Million

...
既然大家對記憶體定址這麼有興趣, 那問一個問題,
以上的PAE定址中, 多出來的4bit 定址(36bit-32bit=4bit), 到底藏在那裏

我看下列wiki (http://en.wikipedia.org/wiki/Physical_Address_Extension) 貼出來的圖, 完全沒有PAE那多出來4bit的蹤跡

該不會是內藏在OS內被OS私下做掉了吧

PAE with 4 kB pages

引用:

作者zergqq

pae的問題可以看intel Intel 64 and IA-32 Architectures
Software Developer’s Manual Volume 3A
ch4.4.2 Linear-Address Translation with PAE Paging
新的已經是52bit[51:0]
36bit是Pentium Pro時代
http://www.rcollins.org/ddj/Jul96/

Even when PAE is enabled, only 4 GB of physical-address space can be addressed at any given time. Regardless of how big the page sizes are, only 32 bits of linear-address space are available. To address more than 4 GB of physical memory, CR3 must be changed (thus pointing to a different set of paging structures), or the existing paging structures must be modified (on-the-fly) by the operating system.

所以被我猜對了!

要存取超過4G-- 1.CR3必須變更位址(這OS才有辦法做吧!) or 2.已存在的PAGE架構必須由OS快速地變更.