NightShade737 wrote:
What do you mean by "context switching"?
Oh, P96 isn't free btw, it's Shareware.
Context switching occurs calling the PowerPC processor from the 680x0 one (or vice versa). Calling one CPU from the other involves flushing the caches of both - up to 8K for a 68060 and 32K for a 604. Hence a context switch is an extremely expensive operation. You have to do this when bothe CPUs are talking to the same area of memory in copyback cache mode, because if you dont, there is no guarentee that the two different CPU's caches are in sync.
A PPC p96 makes sense only for
1) A PPC native amigaos in general
2) A seperate driver system for WarpOS (a bit like the way warp3D works with seperate drivers for 68K and PPC)
3) Accelerating offscreen rendering on bitmaps in fast ram. This would involve writing some ppc code to do the normal graphics.library style rendering in these cases
(1) is in progress
(2) is unlikely to be worth the effort since (1) is in progress
(3) is a possibility if you are an experienced coder willing to try and make a suitable patch.
As for the ppc version of cybergraphx for OS3.x. This contained *no* ppc code of any kind. The only difference was that it used the 680x0 side of the ppc.library to allocate memory with 32 byte alignment to satisfy the PowerPC's cache alignment.