Re: [Dri-devel] Re: [Linux-fbdev-devel] DRM and pci_driver conversion
From: Keith Whitwell
Date: Mon Oct 27 2003 - 10:52:42 EST
Jeff Garzik wrote:
On Mon, Oct 27, 2003 at 03:14:11PM +0000, Keith Whitwell wrote:
Jeff Garzik wrote:
Thank you for saying it. This is what I have been preaching (quietly)
for years -- command submission and synchronization (and thus, DMA/irq
handling) needs to be in the kernel. Everything else can be in
userspace (excluding hardware enable/enumerate, of course).
To enable secure direct rendering on current hardware (ie without secure
command submission mechanisms), you need command valididation somewhere.
This could be a layer on top of the minimal dma engine Linus describes.
Certainly.
Graphics processors are growing more general, too -- moving towards
generic vector/data processing engines. I bet you'll see an optimal
model emerge where you have some sort of "JIT" for GPU microcode in
userspace.
You mean like the programmable fragment and vertex hardware that has been
in use for a couple of years now?
I mean, taking current fragment and vertex processing and making it
even _more_ general. Which has already happened, on one particular chip
maker's chip...
I think that generally you can view all the current generation of hardware as
arbitary programmable devices, and most of the graphics drivers are doing
code-generation for that hardware on the fly. This isn't exactly new ground
for graphics drivers as graphics hardware has alternated (I'm told) between
fixed function and programmable cores multiple times now.
In addition, graphics drivers have been doing on-the-fly codegen for the host
cpu since year dot. The orignal software-rasterization SGI opengl drivers for
windows were supposed to be pretty much state of the art in this respect.
Now that the barriers for codegen have lowered so dramatically (see, eg.
http://fabrice.bellard.free.fr/tcc/), it is now feasible to talk of building a
code-generating software rasterizer for mesa.
Keith
Keith
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