Subject: Re: sh4 pmap bug? (Re: port-dreamcast/34243)
To: None <port-sh3@NetBSD.org>
From: Izumi Tsutsui <tsutsui@ceres.dti.ne.jp>
List: port-sh3
Date: 08/24/2006 09:02:58
uwe@ptc.spbu.ru wrote:

> > Maybe we should check virtual cache index in pmap_pv_enter() and
> > allow multiple mappings if VA pages being mapped have the same
> > virtual indexes like mips pmap?
> 
> My reading of Schimmel's book sections 2.2.5 and 3.3.6 is that for
> that to work the cache must use write-allocate so that if we write via
> one alias, we cause the line to be loaded into the cache so that
> references via the other alias pick up the change.

AFAIK, SH4 use virtual indexed cache with physical tags,
so you should refer the section 5.2.6, not 3.3.6.
I.e. no alias could happen if all mapped pages have the same
virtual indexes (colors).
---
Izumi Tsutsui