Subject: Re: ARM cache
To: None <firstname.lastname@example.org>
From: Toru Nishimura <email@example.com>
Date: 01/17/2005 12:16:09
Some more to say for cache design.
Alchemy Au1 cache is designed smart;
- 16KB I and D, virtual address indexed and physical address tagged,
best fit for process model OS,
- 4 way associativity. Note that it means Au1 cache behaves as a
physical address indexed and physical address cache. This
arrangement saves a lot i*norant programmers since the world is
dominated by PA cache processors.
- write back policy, but it does bus snoop. This mean there is *no* need
of busdma_sync() for device driver to work correct.
Some MIPS processors have VA tagged instruction cache. ASID may
or may not be a part of cache indexing. Since instruction cache is not
supposed written, the design decision seems reasonable.
Toru Nishimura/ALKYL Technology, a NetBSD company