Video Memory

[Joep L. Blom]

Ray Parrish wrote:

>>   
> OK, that's what I was using the first time. For some reason when I try 
> it again now it works. I don't know why it tossed an error before.
> 
> Anyway, here are the numbers I get after converting the following memory 
> ranges.
> 
> Memory Range: 0xfb000000-0xfbffffff (rw,non-prefetchable)
> Memory Range: 0xd0000000-0xdfffffff (rw,prefetchable)
> Memory Range: 0xfc000000-0xfcffffff (rw,non-prefetchable)
> Memory Range: 0x30000000-0x3001ffff (ro,prefetchable,disabled)
> 
> For each range above I subtracted the first number from the second after 
> converting them to decimal. I then divide that result by 1024 twice to 
> convert to MB's. Here are the results I get for each row.
> 
> 15.999999046
> 255.999999046
> 15.999999046
> 0.124999046
> 
> Adding those together gives the result. -
> 
> 288.124996185
> 
> If I only divide the last memory range by 1024 once I get this result.
> 
> 127.999023438
> 
> So... I'm not too sure what this is saying, as I do not know what the 
> memory ranges are specifying for sure. The second memory range matches 
> the reported 256 MB's reported by most utilities in Ubuntu, and dividing 
> the last memory range by 1024 only once matches 128 MB's but that 
> decimal number before division is only 131070.999658496 so if it's in 
> bytes it doesn't make sense to only divide once.
> 
> Anybody out there write device drivers for video cards?
> 
> I guess I'll just have to continue to be mystified as to how much memory 
> my card is actually using.
> 
> Later, Ray Parrish
> 
Ray,
This URL is I think of interest for you.
http://www.folder101.com/CompHardware/Notes/MemMap/MemoryMap.htm
Joep