site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com On Jan 17, 2005, at 7:40, Stéphane Sudre wrote: Cheers, Justin -- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | Some people have a mental | horizon of radius zero, and | call it their point of view. | -- David Hilbert *--------------------------------------*-------------------------------* _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... Is there a documentation explaining somewhere very clearly how a 32 bits process is running in a 64 bits capable OS? Because I'm wondering what kind of address is ok for copyin when the address-space in the kernel is 64 bits. I have some problem understanding how providing my user space address from a 32 bits process is going to work in every case when the address space can be 64 bits. Unless 32 bits processes can't be executed in the last 32 bits of the 64 bits address space. Maybe it will help to realize that, for copyin/copyout, there is always magic around to handle the mapping between address spaces. This mapping makes sure that the address/address-space pairs are properly translated so that the result is a "move a byte from here to there" instruction that the computer can execute. Generally, the magic takes the form of mapping registers in an MMU. Keep in mind that, even in yesterday's G3 and G4 processors, this same magic has to occur to ensure that the virtual addresses seen, separately, by user and kernel instructions get translated to physical addresses (like user space, the kernel address space is mapped). For more details, you should look at a CPU manual (available, I think, on IBM's website). As Shawn has tried to point out, the plan for Mac OS X is to stay 32-bits, while user spaces are (selectively) widened to 64 bits, so in fact, your question should be inverted. This email sent to site_archiver@lists.apple.com