Messages in this thread | | | Date | Mon, 18 Sep 2006 15:39:36 +0200 | From | Helge Hafting <> | Subject | Re: How much kernel memory is in 64-bit OS ? |
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yogeshwar sonawane wrote: > On 9/16/06, yogeshwar sonawane <yogyas@gmail.com> wrote: >> Hi all, >> >> We all know that in 32-bit OS, total 4GB memory space is divided in >> 3(user) + 1(kernel) space. >> >> Similarly, what is the division/scenario in case of 64-bit OS ? >> >> Any reference/explanation will be helpful. >> >> thanks in advance. >> >> >> Yogeshwar >> > > On similar lines, some time back, i read that, to accomodate large > physical memory , > the 3G/1G layout is modified to have 4G/4G partition. But if somebody > can focus the light on following things, it will be helpful. > 1) what was the requirement of 4G/4G layout ? It offers more memory than 3G/1G. This is an improvement, so of course it is the chosen way. It was not required - you sure can use a 3G/1G split on a 64-bit processor - but why introduce an artifical limitation?
The requirement for using a 4G/4G split is to have a processor that support 64-bit adressing as well as 32-bit backward compatibility. > 2) how it is managed ? The kernel runs in 64-bit mode, offering the 4G/4G stuff for 32-bit processes.
> 3) how HIGH_MEMORY concept is related here. high memory is a quirky way of supporting more than 4G on a 32-bit processor. A 64-bit processor support much more than 4G, so no need for tricks that work around the limitations of 32-bit processors.
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