On Sat, 3 Aug 2002, Daniel Sheltraw wrote: >Date: Sat, 03 Aug 2002 09:45:57 -0600 >From: Daniel Sheltraw <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED] >Content-Type: text/plain >List-Id: General X Discussion <xpert.XFree86.Org> >Subject: Re: Option accel question > >Michel > >Thanks for the reply and thanks for helping us get an answer >to our MB problem that Marc ultimately solved. > > >> > Is the accel option implemeted using PCI DMA. I do not really >> > understand what accel is all about. Can someone please shed a >> > little light on the subject for me :-) ? >> >> Short answer: it depends on chip, driver and configuration. :) >> >> Slightly longer answer: most accel is done with MMIO access to chip >> registers. > >How does using the MMIO accelerate graphics? Confused. I just really >do not know what acceleration means.
Video hardware acceleration is the implementation in the video hardware itself of common graphics primatives and operations. Without hardware acceleration, the CPU has to do all the work. The CPU calculates the pixels when drawing lines, polygons, etc. and writes them into video memory. The CPU does all the work. With a 2D acceleration engine, like all video hardware has nowadays, instead of the CPU doing all this work, the CPU merely tells the video card "draw a rectangle with these co-ordinates", then the video hardware's 2D acceleration engine draws that rectangle internally on the video card itself. This moves the drawing logic off the host CPU and onto the video card. There are all sorts of operations which are accelerated in hardware including line drawing, rectangles, fills, blitting images, etc. MMIO is memory mapped IO, which maps the hardware's IO register space into the memory map. This is one way of communicating with the hardware. -- Mike A. Harris Shipping/mailing address: OS Systems Engineer 190 Pittsburgh Ave., Sault Ste. Marie, XFree86 maintainer Ontario, Canada, P6C 5B3 Red Hat Inc. http://www.redhat.com ftp://people.redhat.com/mharris _______________________________________________ Xpert mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xpert
