From: Kalle Pokki <kalle.pokki@iki.fi>
To: Dan Malek <dan@embeddededge.com>
Cc: linuxppc-embedded@ozlabs.org
Subject: Re: CPM2 early console
Date: Fri, 30 Sep 2005 22:10:54 +0200 [thread overview]
Message-ID: <433D9BCE.5000909@iki.fi> (raw)
In-Reply-To: <2c578118c5d984e6e87ac3c073469866@embeddededge.com>
Dan Malek wrote:
> On Sep 30, 2005, at 9:22 AM, Alex Zeffertt wrote:
>
>> Are there any drawbacks to this approach?
>
> The general system performance is going to suffer,
> and if you really have a cache coherency problem
> it only solves the write case and not the read case.
The read case seems to be solved by setting the appropriate GBL bits in
the parameter ram areas, since the buffers work correctly in both
directions by just setting cache write-through and coherent (coherent
alone won't help). Still, there must be a correct way of doing this, but
I think I have already tried modifying every register that sounds
related. The errata doesn't list anything useful.
Another way of getting around the problem would be to place the buffers
in a cache-inhibited memory area and have copy-back caches for other
data. I successfully tried this in another application without Linux.
next prev parent reply other threads:[~2005-09-30 20:11 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-22 16:02 CPM2 early console Rune Torgersen
2005-09-22 16:05 ` Kumar Gala
2005-09-23 10:55 ` Kalle Pokki
2005-09-27 14:11 ` Kalle Pokki
2005-09-27 16:39 ` Dan Malek
2005-09-27 20:35 ` Kalle Pokki
2005-09-27 20:48 ` Dan Malek
2005-09-28 10:20 ` Kalle Pokki
2005-09-29 12:24 ` Kalle Pokki
2005-09-29 12:50 ` Dan Malek
2005-09-30 13:22 ` Alex Zeffertt
2005-09-30 13:42 ` Alex Zeffertt
2005-09-30 20:16 ` Kalle Pokki
2005-09-30 13:58 ` Dan Malek
2005-09-30 20:10 ` Kalle Pokki [this message]
2005-09-30 20:28 ` Dan Malek
2005-10-01 5:57 ` Kalle Pokki
2005-10-01 8:24 ` Roger Larsson
2005-10-02 16:59 ` Dan Malek
2005-10-03 7:04 ` Kalle Pokki
2005-10-04 8:13 ` Kalle Pokki
2005-10-04 9:59 ` Alex Zeffertt
2005-10-04 10:16 ` Kalle Pokki
2005-10-04 16:04 ` Dan Malek
-- strict thread matches above, loose matches on Subject: below --
2005-09-22 13:11 Kalle Pokki
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