From: jmk@plan9.bell-labs.com
To: 9fans@cse.psu.edu
Subject: Re: [9fans] drawterm strangeness
Date: Tue, 24 Jun 2003 13:24:21 -0400 [thread overview]
Message-ID: <95c74034a4670cd53c6ca43a793b40d6@plan9.bell-labs.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0306240745060.9880-100000@maxroach.lanl.gov>
On Tue Jun 24 09:46:25 EDT 2003, rminnich@lanl.gov wrote:
> On Tue, 24 Jun 2003, andrey mirtchovski wrote:
>
> > i urge you to turn dma/rwm on.
>
> This seems like something that just "ought to be" on. Why would it not be?
>
> ron
The reason it's not on by default is that the driver currently does not do any
DMA configuration by itself. In order to set up a DMA mode, both the ATA controller
and the drive have to be configured appropriately. Setting the drive is
straightforward, but setting the ATA controller is chip-specific. Instead, the driver
makes the assumption that if you enable DMA, you know that the BIOS has configured
both the drive and the controller correctly and that is not always the case. Plus,
there are combinations of drives and controllers and DMA modes which don't work
correctly, so the driver errs on the side of safety by default. If you know it's OK,
it's easy to put the enable in cpurc.
I did do some work on restructuring the ATA driver to make some of this possible,
but it is incomplete.
prev parent reply other threads:[~2003-06-24 17:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-06-06 0:48 andrey mirtchovski
2003-06-06 6:24 ` Russ Cox
2003-06-06 21:32 ` andrey mirtchovski
2003-06-24 13:41 ` andrey mirtchovski
2003-06-24 13:45 ` ron minnich
2003-06-24 13:50 ` andrey mirtchovski
2003-06-24 14:14 ` boyd, rounin
2003-06-24 17:24 ` jmk [this message]
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