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Old 03-01-04, 10:52 PM   #18
J.F.
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Join Date: Dec 2003
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Quote:
Originally posted by shupienis
Here's an interesting thought/question... OS-X for the Mac G5. The G5 is a 64-bit extension to a 32-bit architecture, just like the current AMD64 and the proposed future Intel Xeon-64. OS-X is a BSD kernel. What's the 64-bit driver status there?

Warmest regards!
// Joe
G5 is not an extension to the 32 bit architecture. You forgot that the PowerPC architecture was just a stripped down version of the POWER architecture, which was 64 bit originally. The PowerPC has ALWAYS had 64 bit instructions and architecture, but in the 32 bit processors, the 64 bit opcodes generate an exception to allow them to be emulated. Motorola's first CPUs were the 601, 603, 604, and 620. The 620 was a 64 bit PPC, while the others were 32 bit. Motorola never bothered to improve the 620, so IBM went back to the latest POWER CPU to make the G5.

Mac OSX 10.3 allows you to freely use 32 or 64 bit operations however you like. However, it restricts you to 32 bit addresses by setting a bit that makes the CPU truncate all pointers to 32 bits. The kernel then converts the 32 bit address into an address in the the 8GB they currently support. All that is immaterial though. Although Apple's drivers support at least 8 GBytes, they are NOT BSD drivers! Apple didn't care for the BSD driver model and tossed it out. They used a model based on the Next Mach-O kernel drivers. So OSX drivers cannot be used with other BSDs, even though OSX is mostly BSD.
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