Increasing MAXPHYS

Gary Jennejohn gary.jennejohn at
Mon Mar 22 11:40:22 UTC 2010

On Sun, 21 Mar 2010 19:03:56 +0200
Alexander Motin <mav at> wrote:

> Scott Long wrote:
> > Are there non-CAM drivers that look at MAXPHYS, or that silently assume that
> > MAXPHYS will never be more than 128k?
> That is a question.

I only did a quick&dirty grep looking for MAXPHYS in /sys.

Some drivers redefine MAXPHYS to be 512KiB.  Some use their own local
MAXPHYS which is usually 128KiB.

Some look at MAXPHYS to figure out other things; the details escape me.

There's one driver which actually uses 100*MAXPHYS for something, but I
didn't check the details.

Lots of them were non-CAM drivers AFAICT.

Gary Jennejohn

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