Re: [Linux-fbdev-devel] fbdev API problems

[Sven <lu...@dp...>]

On Thu, Nov 22, 2001 at 12:34:03AM -0800, Matt Sottek wrote:
> >The framebuffer itself is pretty safe to export to userland.
> 
> I assume you mean to allow people to mmap the framebuffer? Yes this can
> usually be safe, but only the screen data. Most chips use graphics
> memory of some type for dma command buffers. Most chips cannot safely
> give you full access to such memory areas. The sysmem_start and
> sysmem_length seem to cover the whole graphics region, not just the
> visible framebuffer. This is likely not safe.

DMA is not useable outside of the DRI anyway for now, or do you know of any
userland app doing this ?

I guess you need to have root access to the fbdev or something such to be able
to do dma, not sure though.

Anyway, even X is not able to do DMA outside of the DRI setup. I would have
liked it when writing Xv support for the permedia3 chip.

Friendly,

Sven Luther