Considering the fact that both Ubuntu and Elementary require SSE to boot, I'd wait to get decoding fixed. I wrote a test kernel module that reliably reproduces your issue on qemu edu device. Whenever QEMU prints Unimplemented handler Instruction pointer only moves two bytes further, instead of the instruction length. That corrupts code execution as the next instruction after unimplemented handler is decoded from the wrong address.
-- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1798451 Title: HVF linux on OSX hangs 2nd time started after adding socket Status in QEMU: New Bug description: Robs-MacBook-Pro-2:~ robmaskell$ qemu-system-x86_64 --version QEMU emulator version 3.0.0 Host: MacOS - 10.13.6 Model Name: MacBook Pro Model Identifier: MacBookPro14,3 Processor Name: Intel Core i7 Processor Speed: 2.8 GHz Number of Processors: 1 Total Number of Cores: 4 L2 Cache (per Core): 256 KB L3 Cache: 6 MB Memory: 16 GB Guest OS: Elementary Linux Loki 0.4.1, patched up to date Command used to start QEMU: qemu-system-x86_64 \ -name ElementaryLokiDev \ -machine pc,accel=hvf \ -cpu max \ -smp cpus=2,sockets=2,cores=1,threads=1,maxcpus=2 \ -numa node,nodeid=0 \ -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=0,socket-id=1 \ -m 8G \ -vga vmware \ -hda e4.qcow2 Symptoms: Started without the -smp / -numa commands to install the OS, then added -smp / -numa and the machine boots and lscpu reports extra cpu as expected. Restart VM and it hangs on startup. Remove -smp / -numa and machine starts again. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1798451/+subscriptions
