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Date:      Mon, 9 Oct 2006 13:45:57 -0400
From:      Jung-uk Kim <jkim@FreeBSD.org>
To:        freebsd-amd64@FreeBSD.org, John-Mark Gurney <gurney_j@resnet.uoregon.edu>
Subject:   Re: amd64 agp driver bug?
Message-ID:  <200610091346.02064.jkim@FreeBSD.org>
In-Reply-To: <20061007214336.GJ793@funkthat.com>
References:  <20061007214336.GJ793@funkthat.com>

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On Saturday 07 October 2006 05:43 pm, John-Mark Gurney wrote:
> I was looking at the agp driver and the BIOS and Kernel Developer's
> Guide, and noticed that it appears we program the page register
> incorrectly...
>
> Currently we do, in sys/pci/agp_amd64.c:
>         sc->gatt->ag_virtual[offset >> AGP_PAGE_SHIFT] = physical;
>
> but according to Table 38 in the guide, it looks like it should be:
>         sc->gatt->ag_virtual[offset >> AGP_PAGE_SHIFT] =
>             (physical & 0xfffff000) | ((physical >> 28) & 0xff0) |
> 1;
>
> To support physical addresses above 4G...
>
> Has anyone used AGP w/ >4GB of memmory?  I'm also puzzled by the
> fact that the guide says to set bit 0, but we don't do that...

As you can see, this part of the documentation is very 
confusing. :-(  I'll take care of it soon.

Jung-uk Kim



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