> From: Vasant_-_Kanchan@cup.portal.com
> Date: Mon, 20 Nov 95 20:24:48 PST
> 
>    Hi,
> 
>       Can some one explain to a novice what is the problem
>    with the  BSD ( Mach ) VM system ?. The seperation of the machine
>    dependent parts into the pmap module seems like a good
>    idea. Only recently I have been looking at the BSD lite VM code.
>    So my knowledge is limited.
> 
>    Thanks.
> 
>    Kanchan
>    vasant_kanchan@cup.portal.com

The main problem is that the VM system keeps one cache (of pages)
and the kernel keeps another (of disk blocks) and the two are not
coherent.  (You can get different data from mmap vs read).

Gordon