Screen corruption in 2.4.18
Hi,
I have an i840 motherboard with dual 733 MHz PIIIs and a Matrox G400 MAX, and I am also seeing console corruption with 2.4.18. The difference with me is that I *only* see it when I am using xine (CVS) and the SyncFB video plugin, possibly the Xv video plugin sometimes too. When I kill xine, the regular multicoloured rectangle disappears from the console.
Obviously, this isn't something that I would normally notice - I wouldn't have noticed at all if the CVS xine hadn't locked up on me in full-screen mode, forcing me to turn to a console to kill it.
A few other things:
- since I have about 1.25 GB of RAM, I have enabled a 256 MB AGP aperture.
- I am using XFree86 4.2, but with the mga.o module that is native to Linux 2.4.18. I have not installed the Matrox HAL X module.
Whatever is causing this console corruption, it doesn't seem to be a VIA bug (in my case, anyway).
Chris
On Tue, 2 Apr 2002, Chris Rankin wrote:
[SNIPPED...]
Quoted 3 lines
A few other things:
- since I have about 1.25 GB of RAM, I have enabled a 256 MB AGP aperture.
What? 'since amount of RAM' has nothing to do with AGP aperature. The aperature should be the same as the amount of AGP shared RAM used for the screen-card on-board graphics. This is normally set by the BIOS but can be reset if the BIOS doesn't 'understand' your screen card.
So, unless you have 256 MB on your screen board, typically 32 MB for high-resolution true-color boards, you will be disabling PCI hardware hand-shaking for a lot of addresses above your screen board. This can make DRAM-controler, controlled RAM accesses interfere.
Cheers,
Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
Windows-2000/Professional isn't.
--- "Richard B. Johnson" <[email protected]>
Quoted 16 lines · Chris Rankin
[SNIPPED...]
Quoted 3 lines
A few other things:
- since I have about 1.25 GB of RAM, I haveenabled a 256 MB AGP aperture.
What? 'since amount of RAM' has nothing to do with AGP aperature. The
aperature should be the same as the amount of AGP shared RAM used for
the screen-card on-board graphics. This is normally set by the BIOS but
can be reset if the BIOS doesn't 'understand' your screen card.
Quoted 8 lines
So, unless you have 256 MB on your screen board,
typically 32 MB for
high-resolution true-color boards, you will be
disabling PCI hardware
hand-shaking for a lot of addresses above your
screen board. This
can make DRAM-controler, controlled RAM accesses
interfere.
I set the AGP aperture based upon the following information:
"The AGP aperture is an area of system RAM reserved for use by the AGP card for storing textures if it needs to. The RAM is available for use by the system as normal if not used by the graphics card."
...
"It is generally advised to set the AGP aperture to half the system RAM ."
Therefore, it seemed reasonable to maximise my AGP aperture size for all and any conceivable textures (I have system RAM to spare), with no harm done. Admittedly, 256 MB does seem excessive, but anyway ... ;-).
Chris
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Quoted 20 lines · On Tue, 02 Apr 2002 22:43:03 +0100 Chris Rankin <[email protected]> wrote:
Hi,
I have an i840 motherboard with dual 733 MHz PIIIs and a Matrox G400 MAX, and I am also seeing console corruption with 2.4.18. The difference with me is that I *only* see it when I am using xine (CVS) and the SyncFB video plugin, possibly the Xv video plugin sometimes too. When I kill xine, the regular multicoloured rectangle disappears from the console.
Obviously, this isn't something that I would normally notice - I wouldn't have noticed at all if the CVS xine hadn't locked up on me in full-screen mode, forcing me to turn to a console to kill it.
A few other things:
- since I have about 1.25 GB of RAM, I have enabled a 256 MB AGP aperture.
- I am using XFree86 4.2, but with the mga.o module that is native to Linux 2.4.18. I have not installed the Matrox HAL X module.Whatever is causing this console corruption, it doesn't seem to be a VIA bug (in my case, anyway).
Quoted 7 lines
Chris
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I'm having the same problem, just that this happens when I've been using mplayer with the -vo vesa parameters. I also have this problem with the 2.4.17 kernel.
Signature · 2 lines
-- Best regards, Erik
Quoted 44 lines · On Tue, 2 Apr 2002, [iso-8859-1] Chris Rankin wrote:
--- "Richard B. Johnson" <[email protected]>
Quoted 16 lines · Chris Rankin
[SNIPPED...]
Quoted 3 lines
A few other things:
- since I have about 1.25 GB of RAM, I haveenabled a 256 MB AGP aperture.
What? 'since amount of RAM' has nothing to do with AGP aperature. The
aperature should be the same as the amount of AGP shared RAM used for
the screen-card on-board graphics. This is normally set by the BIOS but
can be reset if the BIOS doesn't 'understand' your screen card.Quoted 8 lines
So, unless you have 256 MB on your screen board,
typically 32 MB for
high-resolution true-color boards, you will be
disabling PCI hardware
hand-shaking for a lot of addresses above your
screen board. This
can make DRAM-controler, controlled RAM accesses
interfere.I set the AGP aperture based upon the following information:
"The AGP aperture is an area of system RAM reserved for use by the AGP card for storing textures if it needs to. The RAM is available for use by the system as normal if not used by the graphics card."
...
"It is generally advised to set the AGP aperture to half the system RAM ."Therefore, it seemed reasonable to maximise my AGP aperture size for all and any conceivable textures (I have system RAM to spare), with no harm done. Admittedly, 256 MB does seem excessive, but anyway ... ;-).
Quoted 4 lines
Chris
From Page 153, "The BIOS COMPANION" ISBN 188967120-7
"The AGP Aperture Size is the amount of system memory for the AGP card, so host cycles hitting that area are forwarded to that card without translation..."
This may be causing confusion because it really should read "amount of system address space". Too many writers interchange the word "memory" for "address space".
No graphics cards, on their own, or with their own BIOS, use any "system memory". They can't. They don't "own" any. Of course, when you run X, X will own some system memory that it allocated via mmap(), and it uses it in conjunction with your AGP card. The internal RAM within the AGP card is the only RAM in "owns". This is accessible to the CPU as well as the card electronics. The address range through which the CPU can access this high-speed RAM is called the Graphics Aperture and/or the AGP Aperture.
This is the same thing as (page 139), "VGA Frame Buffer Size" for the older PCI/VGA boards.
So, if you set your AGP aperture size to overlap address-space where memory exists, you will probably see streaking and flashing (snow) on the screen. The bus-contention will also slow your machine during RAM access and may even cause data corruption in RAM. In other words, if you have 32 MB of RAM in your screen-card, set the aperture size to 32 MB, not (!) 256 MB.
Cheers,
Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
Windows-2000/Professional isn't.
--- "Richard B. Johnson" <[email protected]>
Quoted 3 lines · wrote:
if you have 32 MB of RAM in your screen-card, set
the aperture size
to 32 MB, not (!) 256 MB.
OK, I've reset the aperture to 32MB and I no longer get screen corruption with xine. However, it appears that there are a lot of different opinions on how to best set the AGP aperture:
http://www.lostcircuits.com/advice/bios2/12.shtml
Chris
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