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Apple already supports ARM so they have the whole toolchain, most of their operating system, and many frameworks ported. Most of the heavy lifting was done in
by CoolGuySteve 6y ago
Apple already supports ARM so they have the whole toolchain, most of their operating system, and many frameworks ported. Most of the heavy lifting was done in Project Purple (aka the first iPhone).
Porting from PPC to x86 was arguably more difficult as a lot more of the framework code had endianness assumptions baked in.
- qalmakka 6y agoAs Steve Jobs himself said in the famous Mac Intel keynote, Mac OS X ran on Intel from day one, "just in case". After all Darwin has always supported x86, and NEXTSTEP ran fine on x86 too, so probably it was not that difficult from a core system standpoint migrating to x86.
- gsnedders 6y ago> Porting from PPC to x86 was arguably more difficult as a lot more of the framework code had endianness assumptions baked in. Did it? The code they inherited from NeXT didn't assume endianness, and until Rhapsody Developer Release 2 they shipped x86 builds. Some applications like iTunes ran on Windows, with a partial port of the Cocoa libraries underlying them (this, too, was a descendent of old NeXT support for Windows). It's entirely plausible that Apple didn't have to do much; as they said at the time, they never stopped supporting x86 after Rhapsody Developer Release 2, and they had the OS running on x86 the entire time. I'd assume from the point of view of most developers working on OS X they simply had requirements to avoid endian assumptions, etc., and occasionally the team maintaining x86 support would send a nondescript patch to "fix the endianness assumption".