Re: address spaces in kernel

[Fawad Lateef <fawadlateef@xxxxxxxxx>]

On 9/3/05, Thayumanavar Sachithanantham <thayumker@xxxxxxxxx> wrote:
> 
>  # you have specified that   the 0 - 896 MB of physical RAM being mapped to
> 3-4Gb in virtual addr space. How can this be possible, usually  a standalone
> system will have  256/512 MB of RAM.  Can you please make me clear about
> this? 
>  I does mean that there exists always a mapping of virtual addresses between
> 3-4G to  physical addresses which range from 0 to 896 MB(permanent
> mapping).In a 256/512 MB < 896 MB, there will be  mappings of the virtual
> addresses in range 3-4G to the corressponding physical addresses in the
> range 0-256/512 MB. 
> Hope this clears your doubt. 
>   
> Thayumanavar.
>  
>  

I also want to add one thing !!!! the 0 - 896MB physical addresses can
be calculated by subracting PAGE_OFFSET(in default (3G/1GG) it is
0xC8000000) from the Virtual Address. So this means that for 512MB
System the Virtual addresses for Kernel will be from 3G to 3G +
PAGE_OFFSET + 512MB ...... (CMIIW)


-- 
Fawad Lateef

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