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Followup to: <787b0d920606062011j21083e80v659228a7565ecfab@mail.gmail.com> By author: "Albert Cahalan" <acahalan@gmail.com> In newsgroup: linux.dev.kernel > > The bigger problem is that 32-bit code has fewer CPU registers. > (nobody has done an ILP32 ABI for long mode) This is slow. > The issue isn't the ABI, the issue is that the processor doesn't support it, since some of the opcodes mean different things in 16-, 32- and 64-bit mode. The opcodes which access the high half of the register sets (REX prefixes) in 64-bit mode are INC and DEC instructions in 16- and 32-bit mode. AMD was apparently considering adding a "REX32" mode at some point, but rather predictably noone was interested enough to make it worthwhile. -hpa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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