PaX's ASLR implementation for 64-bit x86 machines is much stronger than Linux's default 64-bit ASLR implementation. My question is simple, why is PaX's implementation not the default one?
I'm assuming this is somehow related to compatibility issues, that it breaks the functionality of certain programs? Or breaks something else, somehow?
Which programs (examples, if anyone knows) does it break, if any, and more interesting why does it break them?
The other possibility would be a higher performance penalty, but after looking at the source code I can't figure out why it should be slower. Feel free to correct me on this. I'm assuming it is related to the former though, compatibility.