dma to vmem

[Adek336]

Hello.

It seems impossible to make the dma write in the video buffer.

I heard vmem is a window in the card's memory, so perhaps that's why it can't work?

Adrian.

[df]

in the old days, it was faster to use dma transfers to get stuff into the video memory for games than direct memory copies... so it can be done.

i cant think of a reason why it cant be done today, since its just another memory hole.

iirc.. not 100%, you have to give it a physical address, so if your in pmode and you have virt mapped memory, you cant give it a logical address.

[Anton]

You can write to a video buffer, you just need to map it to memory adress space using PCI or AGP interface. Usualy OS put this memory at the end of physical(RAM) memory.
Anton.

[carbonBased]

It's possible, but not overly useful, now-a-days.

I've heard of projects like this a few years back, but most came to the conclusion that writting directly to video memory is a lot less hassle and, in fact, faster (with 32 or, now, 64-bit writes).

Cheers,
Jeff