Video Memory

[Ray Parrish]

Joep L. Blom wrote:
> Ray,
> Using the calculator in Gnome (Scientific form) it calculates without 
> any problem the hex to dec conversion:
> FBFFFFFF = 4227858431
>
> Choose Hex and enter the figures (of course without 0x). Then choose Dec.
> That's all.
> Joep
>   
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

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