CPM2 early console

Alex Zeffertt ajz at cambridgebroadband.com
Fri Sep 30 23:42:30 EST 2005

On Fri, 30 Sep 2005 14:22:18 +0100
Alex Zeffertt <ajz at cambridgebroadband.com> wrote:

> Till now I have worked around this problem by calling
> dcache_invalidate_range() and dcache_flush_range() before and after
> accesses to these areas.  I'm now considering changing to Kalle's
> way of doing it.
> Are there any drawbacks to this approach?

To answer my own question: yes there is a drawback.

I've just done some performance tests on my driver.  In the first
test the driver uses invalidate/flush calls to keep the cache
coherent. In the second test I just use Kalle's mod to setbat().

In the second test the perfomance of the driver is roughly 1/3 of the
performance in the first test.

What I really want is a way of asserting GBL whenever the CPM accesses
ANY memory area other than DPRAM.  Hm.


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