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 09:50:59
uwe@ptc.spbu.ru wrote:
> Right, but 5.2.6 says:
>
> "... The case of a single process attaching the same shared
> memory region two or more times within its own address space is
> the same as described in the previous chapters (see Section
> 3.3.6)."
Ah, okay, but anyway such aliases could only happens
if shared pages have the different virtual indexes.
i.e. maybe we should fix ld.elf_so to consider virtual
indexes (colors) on mappings.
The SH4 programming manual also says:
>> When address translation information whereby a number of
>> 4-kbyte page UTLB entries are translated into the same
>> physical address is recorded in the UTLB, ensure that
>> the VPN [13:12] values are the same.
BTW, it also says:
>> When multiple items of address translation information use
>> the same physical memory to provide for future SuperH RISC
>> engine family expansion, ensure that the VPN [20:10] values
>> are the same.
It looks Renesas consider that they would release SH4 family with
virtual cache which has 2^9 indexes... (Umm, unlikely)
---
Izumi Tsutsui