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== Emulators == It's not just hardware that implements the i686 instruction set, software emulators can too. So which emulators support multi-byte NOPs? In 2006 [https://sourceforge.net/p/bochs/code/7216 Bochs r7216] was committed, adding support for the multi-byte NOP opcode as long as Bochs was compiled to emulate an i686 or newer. Later in 2007 [https://sourceforge.net/p/bochs/code/7973 Bochs r7973] was committed, marking 0F 19 through 0F 1E as multi-byte NOPs based on AMD documentation. They didn't link to the documentation but it makes sense to me. In 2006 [https://git.qemu.org/?p=qemu.git;a=commitdiff;h=e17a36ce41bc76abeceb QEMU r2145] was committed and made all hinting NOPs execute as multi-byte NOPs. This made it in to QEMU 0.9.0 which makes the Debian bug report reporting QEMU 0.9.1 as crashing due to NOPs surprising. Furthermore these NOPs are available on every emulated x86 CPU, 32-bit or 64-bit, regardless of whether it should have it or not. In 2007 [https://github.com/mirror/vbox/commit/cb39b37cad08c79c5096fcd5dd69ad6997ee418b VirtualBox r2422] imported QEMU's i386 interpreter and gained multi-byte NOP support. In 2020 [https://github.com/sarah-walker-pcem/pcem/commit/b973755ca376dbb47c3a8c85a53f4058f0ccc54d Add hintable NOPs for Pentium Pro and II.] was committed to PCem. In 2022 [https://github.com/joncampbell123/dosbox-x/pull/3390 src/cpu: Implement hinting NOPs] was merged to DOSBox-X, the only DOSBox variant that supports Pentium Pro and newer CPUs.
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