In message <20040628221600.GD21541@netbsd.org>, Bill Studenmund writes:
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>On Mon, Jun 28, 2004 at 05:09:04PM -0400, Steven M. Bellovin wrote:
>> Following up yet again...
>>=20
>> The log shows the following text:
>>=20
>> II) Loading sub module "ddc"
>> (II) LoadModule: "ddc"
>> (II) Loading /usr/X11R6/lib/modules/libddc.a
>> (II) Module ddc: vendor=3D"The XFree86 Project"
>> 	compiled for 4.4.0, module version =3D 1.0.0
>> 	ABI class: XFree86 Video Driver, version 0.7
>> (II) I810(0): VESA VBE DDC supported
>> (II) I810(0): VESA VBE DDC Level none
>> (II) I810(0): VESA VBE DDC transfer in appr. 0 sec.
>> (II) I810(0): VESA VBE DDC read failed
>
>I'm sorry that I'm about to state the obvious, but I'd suggest printf()=20
>debugging to figure out why the transfer fails. Since it completes so=20
>fast, I expect something simple is wrong, somewhere along the way. Like=20
>maybe we're not enabling something that's needed, say we're trying to do=20
>DDC out a port that's not turned on..
>
>Sorry I know so little about this as to be no more help..
>

Well, that's my problem, too -- I do *not* understand much of the X 
structure.  But I did look around before I posted.

Grep tells me that the "read failed" message is coming from 
vbe/vbe.c.  It, in turn, is calling xf86ExecX86int10, which is calling 
the BIOS, I believe.  I *really* don't know how to put printfs there...
(There is an option to disable int10 processing; selecting it produces 
"VBE Initialization failed".)

		--Steve Bellovin, http://www.research.att.com/~smb