3 ms·
I'd guess that PAE on x86 systems might really hurt with this. Basically any system where the memory model is one of segment + offset will run into trouble with
by peteri 10y ago
I'd guess that PAE on x86 systems might really hurt with this. Basically any system where the memory model is one of segment + offset will run into trouble with pointer comparisons. Ever since the 8086 I've assumed that pointer math is tricky and non portable (see http://catb.org/jargon/html/V/vaxocentrism.html http://catb.org/jargon/html/V/vaxocentrism.html for the 80s version of the same problem)
- userbinator 10y agoPAE means pointers that need to hold at least 36 bits, but in practice I don't think anyone, OS developers included, would ever treat the whole PAE address space as one entity and represent addresses with a single pointer.
- cesarb 10y agoPAE means you have longer physical addresses, but pointers are always virtual addresses. That is, the difference is only visible in the layout of the page tables. Segment+offset is something else, but even on 32-bit x86 the segments were almost always set to base 0, and AMD64 dropped most of the segment mechanism. The exception on both is using segments to access thread-local data, but even then it's used just as an offset into the same flat address space.