yes,no,yes,no
Originally posted by beatle888
the question:
will quark or any 32bit app have to be optimized for the new (hope) 64bit chip?
i remember reading here that it wasnt necessary...32bit code can run fine on a 64bit chip.
Several answers....
IBM claims that the PPC970 will run 32-bit code fine, and even 32-bit operating systems with very minor changes. (Not surprising, since the operating system usually needs some minor changes for every new chip, motherboard or other widget.)
Answer1: No, 32-bit applications won't need to be optimized to run on the 970, and Panther won't even need to support 64-bit.
If Panther does support partial or full 64-bit addressing, then we can assume that it supports a 32-bit mode for 32-bit applications. The alternative means that no existing applications will run on Panther on a 970, somewhat limiting its appeal.
Answer2: No, 32-bit applications won't need to be optimized to run on 64-bit Panther on a 970. They won't pick up any benefits from 64-bit, but they'll run as they always have.
The 970 chip has more functional units and parallelism than the G4. which means that compilers can generate code sequences that can exploit the extra power of the chip. The code should execute correctly on PPC chips (with allowance for AltiVec, of course). It is likely that an instruction sequence that runs the fastest on a 970 is not the same as the sequence that runs the fastest on a G4 - although both sequences will run correctly on both chips.
Answer3: Yes, 32-bit applications can sometimes be optimized by simply recompiling the code with a compiler that understands how to generate the fastest PPC970 code sequences. That might make them run a bit slower on the G4, but manufacturers usually optimize for the fastest systems.
If a 32-bit application is to really exploit 64-bits, it will take serious modifications and testing. For most applications, however, there's little benefit from 64-bit - so this is a moot point.
Answer4: Yes, applications will need modifications (from modest to extensive) and testing to optimize for 64-bit addressing.