How much video memory is available in VESA?

[Slasher]

Hi people,
Have been working on VESA stuff. I have 2 running computers with Nvidia cards. 1st card is 32mb Riva TNT2 and the 2nd is 256mb FX5500.
The vesa infomation returned for the cards are fine except for the Memory size field (TotalMemory in vesa 3 doc).

The TNT2 card says I have 4mb for VESA but has 32mb on the card.
The Fx5500 card says I have 256mb for VESA and has 256mb on board.

Now the question - Is there a limit on how much video memory we can access on the video card using vesa?

I was going to use this memory size field to map the physical mem into the page directory and setup MTRRs for graphics.


ps Boch returns 4mb as the vesa total memory

[JAAman]

i doubt there is a limit (though i havent spent serious time with the VBE3 docs), but it is possible that a card doesnt support all of it in VESA (such as your first card -- mabey its VESA BIOS cannot access all of its internal memory)

as for bochs, i wouldnt expect more than that -- though you didnt say which video controller you had set bochs to use (you do know that within bochs you cannot access the real video card, right? you are useing an emulated card set in your bochs script -- and there is more than one)

[Dex4u]

@Code Slasher, If you need code for setting MTRR to WC, i have some from my OS, you can look at, it give me a 70% inc in FPS in vesa, just by implementing it.

[Slasher]

@JAAman , How can I access the real video card in bochs? I'm using the emulated card at the moment.

@Dex4u, thanks for the offer. I'm not having problems with setting the MTRRs. I don't want to setup a 256mb WC area and then not actually have the whole 256mb to use.

Please keep the ideas coming.

Thanks a lot.

[Kemp]

You don't use the real card in Bochs, that's the whole point of it being an emulated machine. Even if Windows would allow that level of access to a userland program, you would have to be uber-careful to set everything back how you found it or Windows and the card's drivers would have no idea what was going on with it.