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Date: Sun, 5 Jul 2009 16:16:10 +0200
From: Gary Jennejohn <gary.jennejohn@freenet.de>
To: Alexander Motin <mav@FreeBSD.org>
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Cc: freebsd-arch@freebsd.org
Subject: Re: DFLTPHYS vs MAXPHYS
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On Sun, 05 Jul 2009 11:38:23 +0300
Alexander Motin <mav@FreeBSD.org> wrote:

> Gary Jennejohn wrote:
> > I wonder whether all drivers can correctly handle larger values for
> > DFLTPHYS.
> 
> There are always will be drivers/devices with limitations. They should 
> just be able to report that limitations to system. This is possible with 
> GEOM, but it doesn't looks tuned well for all providers. There are many 
> places, when DFLTPHYS used just with hope that it will work. IMHO if 
> driver unable to adapt to any defined DFLTPHYS value, it should not use 
> it, but instead should announce some specific value that it really supports.
> 

This would be the correct way to do things.

I remember back in the good-old-days, circa 1985, disk drivers _always_
did their own PHYS handling so that utilities could pass in whatever
value they wanted to use for the size.  Of course, that meant that each
driver reinvented the wheel.

---
Gary Jennejohn