KQEMU 1.3.0pre10 released - under the GPL
Posted Feb 6, 2007 18:59 UTC (Tue) by mikov
In reply to: KQEMU 1.3.0pre10 released - under the GPL
Parent article: KQEMU 1.3.0pre10 released - under the GPL
To me the really impressive part of QEMU is not the virtualization using the kernel module, but rather the JIT-based emulation (which AFAIK has always been GPL).
When not using the kernel module, QEMU dynamically recompiles all guest instructions to the host instruction set, which makes it much faster than traditional emuilators like Bochs. It is actually possible to run Windows in QEMU in such emulated mode, and it is completely usable. Additionally, in this mode QEMU can emulate x86 with good speed running on any host (e.g. PowerPC). On top of that it is a 100% user node app, with no privileges (doesn't even have to run as root) so it is completely safe and secure.
AFAIK, QEMU uses GCC to generate binary code for the emulated instructions and then simply chains together these binary blobs. This allows it to be (almost) trivially ported to any architecture supported by GCC.
I think there is an opportunity for somebody to improve QEMU by replacing the code generation engine with a hand-tuned one (sacrificing the easy portability to any host). Perhaps LLVM could be used. I think this can bring the emulation speed from its current 10x slowdown to about 3-5x (without any kernel code!). This is a very exciting area.
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