Let's hack the GMA950!

[kaidomac]

I'm starting a new Mini video card thread based on killeen's thread over in the Gaming section of the forum:

http://forum.onmac.net/showthread.php?t=1019

So we know the following so far:

1. The GMA950 video chip can change to match the ram/software requirements
2. Windows machines (non-Apple) with 2gb system ram can have a 224mb video card
3. Apple machines with the GMA950 are capped at 64mb

So our first question is this: how is Apple capping the GMA950? I see three options for limiting the vram:

1. Hardware
2. EFI (new BIOS)
3. Software (driver)

We know that Boot Camp users don't get 224mb video ram with 2gb system ram, although the screenshot in killeen's post shows that it can support up to 224mb based on a system with 2gb ram. So it's probably either hardware or EFI. I'm guessing it's EFI. Can anyone confirm this?

What do we need to do to make this happen? Serpent and I have already hacked the Mini to use a full-sized SATA drive as well as a full-sized ATA drive (actually 2 ATA drives!). The only thing holding it back now is the video card; if we can open it up to 224 megs the Mini can really fly! Once we figure out how Apple is doing it, then we can begin work on a hack.

[kaidomac]

I'll put in the obligatory Apple doc on the GMA950:

http://docs.info.apple.com/article.html?artnum=303407


Mac mini (Early 2006): About the Video Processor

The Mac mini (Early 2006) uses the Intel GMA950 graphics processor for video output. This processor shares the main system memory, allocating a base amount of 80 MB for video and boot processes. This leaves 432 MB of SDRAM available to Mac OS X in a standard system (configured with 512 MB SDRAM).

Mac OS X may make additional main memory available to the graphics processor for texture use beyond the base 80 MB amount mentioned above, depending on the application being used.

For best graphics performance, your Mac mini (Early 2006) ships from Apple with two equal-sized SO-DIMMs installed, one in each slot, for each memory configuration offered from the Apple Store. If you upgrade the memory in your Mac mini (Early 2006), make sure you have matching size SO-DIMMs in each slot for best graphics performance.

[JayMac]

"3. Apple machines with the GMA950 are capped at 64mb"...

What makes you think there is a limit on machines with 2GB, the driver in XP does not report a 64MB limit, its shows 224MB max?

Is there a program we can load to fill the graphics memory and test it?

[JayMac]

I just installed the Sandra test suite. It reports the Intel Mini has 228MB of video ram in XP with 2GB of RAM installed.

[kaidomac]

I just installed the Sandra test suite. It reports the Intel Mini has 228MB of video ram in XP with 2GB of RAM installed.

Yeah, software reports show at least 224mb vram available in XP; I wonder if we can really access all of that. Also, how do we uncap it in OS X? Is it a driver issue or BIOS/EFI thing?

[Mufasu]

I for one am not really concerned about the video performance in osx, but more in xp. Are there any confirmed reports of this, and if so are there framerate/performance meters. The games i'm concerned about playing are:
CS:S/HL2 (just needs to be playable...low settings are fine with me just so long as i can get a decent fr)
UT2k4 (heard it runs like a charm)
HALO (should run fine)
Dawn of War (heard its fine)
WC3 (heard its fine)
and maybe company of heroes, which has fairly low sys requirements, and if the 224mb expansion in winxp is true than it should run fine at lower settings.

I'm also curious, people have said the v-ram expands based on need, but is there anyway of keeping it at a set amount, say 220 or so (in XP that is)? thanks.

[kaidomac]

Mufasa, I haven't made any progress on this. I gave up. It's a bigger project that I wanted to pursue. Also, HL2 runs just fine with the GMA950 at stock settings in XP.