> (Question: what is the negative consequence of making NKPDE much larger than
>  it is?  The number of PDE's used by the kernel should be much smaller than
>  the number used by user pages, shouldn't it?)



> Each of these page tables gives you 4K pages, right?  That's 4K * 4K = 16MB of
> address space, right?

Wrong.  each KPDE maps 1 4k page which contains 4-byte PTEs, each of
which maps a 4k page.

So, it's 1 * (4k / 4) * 4k, so 4MB.


> So with NKPDE=12, the kernel has 12 * 16MB = 192MB of address space to play
> with.

No, 48.



cgd