Re: CVS commit: src/sys/uvm

["Toru Nishimura" <locore64%alkyltechnology.com@localhost>]

Masao Uebayashi <uebayasi%tombi.co.jp@localhost> responds as;

> > The VIPT rule is simple;  just make sure to match colour between
> > VPN and PFN. 
>
> Hmmm.  I've thought that the page colouring constraint is *should*,
> not *must*.

Colour match between VPN and PFN is *must*

If not obeying the rule, it's possible two or more cache index is
selected for given a physical address.

Consider the reason why VIPT alias issue vanishes when
PAGE_SIZE is increased.   It would make the number of
colour into one  _by_matching_ low order bits (= colour
selector field) of VPN and PFN.

Toru Nishimura / ALKYL Technology