“ An OS could be called “64bits OS” because it offers a 64bits ABI to userland applications compiled in “64bit mode”. So, there is no way to put anything above 4GB in your address space to back those 64-bit addresses.”įinally, The Ego on the same Slashdot thread says: But there is only one set of mmap(), etc… traps on the system at the moment (both 10.2.7 and Panther), and they only supports 32bit addresses. “ Your code could use 64-bit addresses after being recompiled.
While there are technical details yet to be revealed by Apple, if there are no 64-bit libraries on Mac OS X, the OS does not support 64-bit applications, in all practicality.Īn anonymous poster on a Slashdot thread (OK, not the most relibable of sources) confirms this: Whenever you compile even the simplest application on an OS, you must link to libraries of some sort.
I have not seen anything yet that implies that new 64 bit addressing versions of the systems libraries and framework will be provided in Panther (I bet they will be recompiled to use 64 bit native math, etc. “Outside of that I believe the user mode libraries/frameworks will remain 32 bit and hence most processes/applications must remain 32 bit (if you are careful of what you use I see no reason you could not use 64 bit addressing in certain tasks). No one really cares how much memory the OS internals use, the key question is can real life applications break the 4GB barrier? One non-Apple poster on the darwin-development list, Shawn Erickson, speculates:
So the kernel in current (10.2.x) and future (10.2.7 and 10.3 Panther) versions of Mac OS X will only support a virtual address space of 2^32 bytes = 4GB of memory. “Yes the kernel’s virtual address space will remain 32bit for the medium term but self-evidently we can address >32bit of physical memory from the kernel.” The basic evidence is from a post on Apple’s darwin-development list by Apple employee (or email account holder at least) Godfrey van der Linden. More and more evidence is out there that applications on Mac OS 10.2.7 and 10.3 cannot address more than 4GB of RAM, which is the limit imposed by 32-bit operating systems. It turns out that Smith’s article on The Register is more or less correct. This had led to a lot of claims that the article is false or misinformed, rather than just unclear, which is certainly is. The basic point of the article is that Mac OS 10.2.7 and 10.3 are not “true” 64-bit OSes, but the article does not clearly explain what a “true” 64-bit OS is. It is also caused a heated argument here on OSNews. A recent article by Tony Smith from The Register titled “ Mac OS X 10.3 Panther will not be a 64-bit OS” caused a good deal of confusion with many people, including me.