do you think applications will be easier than drivers to make 64bit? is that just a question of recompiling, or does it require re-writing from scratch in 64bit?
Applications will generally be easier to port. The 64-bit cleanliness hurdle still applies when making userland applications stable, but the PCI memory mapping quirks shouldn't matter in userland. Everything else (NUMA and extra register usage) is really optional performance tuning.
Optimizing register usage is generally a compiler issue. AMD's NUMA implementation is slightly tricky for multithreaded apps, because the more multiple threads share data, the more traffic will have to go between the inter-CPU HyperTransport links--which incurs a bit of a performance hit.
also, i am almost cerain the answer to this is yes, but, if (or when) intel eventually releases a 64bit Pentium, will it be 100% compatible with 64bit drivers/applications/OS' etc. that have been written based on the Athlon 64?
Well...that's a good question. I can think of two scenarios:
1) AMD64 really catches on before Intel can get a Yamhill(ish) implementation going. In this case, Intel will probably (wisely) make a set of Yamhill extensions 100% compatible with AMD64. W00t!
2) Intel manages to get their Yamhill(ish) implementation going before AMD64 really catches on. In this case, Intel can make theirs just slightly incompatible with the AMD64 instruction set, and due to Intel's dominant marketshare, AMD will be cut out of the 64-bit loop. Even if the AMD64 ISA manages to hang on, we'll be stuck with two divergent, incompatible 64-bit x86 ISAs. Suck! :frown:
I'd consider (1) to be the most likely outcome. (2) is still possible, and there are even rumors of 64-bit Yamhill(ish) extensions in Prescott. Deciding whether Yamhill would be compatible or incompatible with AMD64 will probably be a simple matter of microcode changes, so Intel could make that decision even after committing to a Prescott tapeout.
<i>I can love my fellow man...but I'm damned if I'll love yours.</i><P ID="edit"><FONT SIZE=-1><EM>Edited by kelledin on 08/12/03 01:06 AM.</EM></FONT></P>