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So is the only difference between "x32" (sic) and 32 bit x86 with PAE the fact that "x32" can use full 64 bit registers?
by johnklos 2y ago
So is the only difference between "x32" (sic) and 32 bit x86 with PAE the fact that "x32" can use full 64 bit registers?
- jmmv 2y agoIn part yes, the difference is the ability to access the 64-bit registers, the additional set of registers, and the assumption that SSE is present. But because of all of these, x32 defines a new call convention to optimize function calls.
- kimixa 2y agoI'd argue it's more similar to 64-bit x86, and the only difference between the "standard" x86_64 ABI and x32 ABI is that x32's pointers are 32bit. Everything else matches the 64-bit version - not the 32bit one - the instruction encoding, the extra registers, the minimum isa extensions (x86_64 puts a baseline of sse2), the calling convention advantages etc. etc.
- o11c 2y agoThere are a lot of future-oriented decisions in the x32 ABI, for example 64-bit `time_t` to avoid the Y2038 problem.