Subject: Re: Single file system (buf) read size
To: Manuel Bouyer <bouyer@antioche.lip6.fr>
From: Ignatios Souvatzis <is@netbsd.org>
List: tech-kern
Date: 03/13/2001 21:51:30
On Tue, Mar 13, 2001 at 09:20:41PM +0100, Manuel Bouyer wrote:
> On Tue, Mar 13, 2001 at 10:24:52AM +0100, Ignatios Souvatzis wrote:
> > On Mon, Mar 12, 2001 at 10:19:38PM -0800, Chuck Silvers wrote:
> > > there's the MAXPHYS constant that you should bump up to the maximum i/o size
> > > you want to use.  I wouldn't be surprised if you ran into trouble though,
> > > since I imagine hardly anyone tests drivers with an increased MAXPHYS.
> > 
> > It's worse.
> > 
> > The amiga/dev/asiop driver (and its descendants) have a static area of
> > dma regions allocated in the address space written by the driver and
> > read by the downloaded script code... it's scaled as MAXPHYS / MMUpagesize.
> 
> Same for the MI siop driver.
> The IDE drivers are also limited to 64K/xfer, and that's a hardware limit.

I wonder... wasn't there some driver specific routine to further limit the 
global setting?

Such drivers should implement it.

	-is