[coreboot] how to prevent legacy resource conflictwith multiple VGA cards

Scott Duplichan scott at notabs.org
Sun Oct 31 03:41:05 CET 2010

-----Original Message-----
From: Carl-Daniel Hailfinger [mailto:c-d.hailfinger.devel.2006 at gmx.net] 
Sent: Saturday, October 30, 2010 07:40 PM
To: Scott Duplichan
Cc: coreboot at coreboot.org
Subject: Re: [coreboot] how to prevent legacy resource conflictwith multiple VGA cards

]On 30.10.2010 07:07, Scott Duplichan wrote:
]> Whew, finally solved this problem. 1600 x 1200 32-bit color is now working
]> with the Win7 in-box ATI driver. The problem is that some important
]> information is passed from coreboot to the ATI video driver, and some of
]> it was incorrect. The information is passed by placing it in the last
]> 512 bytes of the frame buffer, so it is easy to look at. The format of
]> the information is in struct ATOM_INTEGRATED_SYSTEM_INFO_V2.
]> I should have thought of this when the slow HT link problem resulted in
]> screen tearing. The driver tries to never let this happen. One of the
]> items passed to the driver is HT link frequency and width. Hard-coded
]> values were used for link frequency and width, and frequency was invalid.
]> Apparently the driver skipped the bandwidth checks because of this.
]> I believe with this change, Win7 will be able to get through setup
]> smoothly and most everything will be working. There are several more
]> patches to submit before mahogany_fam10 will have all of the Win7 changes.

]Awesome detective work, Scott!

Well darn, still not there yet. Last night, I booted in a low resolution
mode and then successfully switched into 32-bit 1600x1200. Now I find
that this mode from the start is not reliable. Also, Microsoft's dxdiag
(direct x test) causes a crash. The ATI Atom table is now identical to
that of the reference BIOS. Debug continues...


]If you ever have the time, please write down all the stuff you had to go
]through to find and fix the bugs you encountered, or at least talk about
]it and record it with your MP3 player so someone else can transcribe it.
]Transcribing may be a task suitable for Google Code-in 2010 because it
]adds documentation about the project.

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