[okl4-developer] ARM_TOP_LEVEL_BITS

[Nelson Tam]

Hi Victor,

On 28/03/2008, at 3:53 AM, Victor Kang wrote:
>
> These days, I’m trying to analyze source code of OKL4.
> But, there is some problem that I cannot understand.
>
> Why is the ARM_TOP_LEVEL_BITS macro defined as 26?
>
> I think it should be defined as 25 because the length of PID is 7 bit.
> Do I think wrong?


The ARM_TOP_LEVEL_BITS value is not related to the length of PID, nor  
the pid-relocation mechanism.  It merely determines the size of the  
top-level page table.

We set it to be 26 so that the 2nd- and 3rd-level page table can be  
roughly the same size for lookup efficiency.
--
(nt)

Nelson Tam