kern/70037: ALI AGP fails / panics system

[Mark Tinguely]

>Number:         70037
>Category:       kern
>Synopsis:       ALI AGP fails / panics system
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Aug 05 15:40:31 GMT 2004
>Closed-Date:
>Last-Modified:
>Originator:     Mark Tinguely
>Release:        FreeBSD 4.x and 5.x
>Organization:
>Environment:
>Description:
      Many ALI based AGP chipsets cannot correct detect the Aperture size.  In FreeBSD 4.x kernels, this causes a panic. In FreeBSD-current just fails to initialize the AGP. The problem is the ALI Aperture size test is wrong. This fix was taken from NetBSD. I do not agree with the mask in the agp_ali_detach() routine and put a "XXX comment". The below patch has been confirmed by another person who has the chipset.
>How-To-Repeat:
      Boot a AGP enabled kernel on certain ALI chipset on FreeBSD 4.x or FreeBSD 5.x.
>Fix:
The following URL is a FreeBSD 4.10-RELEASE and FreeBSD-current (08/05/2004) unified diff to solve the problem:

      http://www.casselton.net/~tinguely/agpali.patch.

This came from NetBSD. Visually, I think the agp_ali_detach() mask does not return the chipset to its original value.
>Release-Note:
>Audit-Trail:
>Unformatted: