From: Frank C. E. <fe...@ai...> - 2002-03-16 16:17:41
|
On Thursday 07 February 2002 12:37 pm, Jose Fonseca wrote: > Could someone of the 3D gurus enlighten this question? More > specifically, what is "pseudo DMA" and what is the relationship between > DMA and the PIO and MMIO modes? psuedo DMA is where you pass a DMA-able command buffer to an interpreter engine that then submits the commands via MMIO. It's of mixed use- it's slower than straight MMIO, if you've got the command structure figured out it can give you a litmus to tell you if you've got problems with the DMA pass (Ex. "It ran in psuedo DMA, why isn't it working right in DMA?" The mach64 has an issue with PPC machines where it just isn't happy with one of the gears rotating in gears, but only if it's being DMAed to the chip- PDMA works fine and both work as expected on x86 platforms... I still haven't quite figured that one out yet.) -- Frank Earl |