graphic: 0.891 KVM: 0.842 performance: 0.837 device: 0.835 vnc: 0.831 permissions: 0.830 PID: 0.802 debug: 0.799 network: 0.792 files: 0.787 semantic: 0.778 socket: 0.771 other: 0.753 boot: 0.677 qemu 2.4.0 with --enable-kvm hangs, takes 100% CPU When starting qemu-system-x86_64 from version 2.4.0 with --enable-kvm, it hangs and takes 100% CPU. The graphical display (SeaBIOS output) is not initialized. There have been multiple reports of this issue in the following thread: https://bbs.archlinux.org/viewtopic.php?pid=1572405 There is no need to load a certain image, it already hangs with the following command: qemu-system-x86_64 --enable-kvm There are three workarounds: - Downgrading the kernel form 4.2.2 to 4.1.6 (according to the forum thread, have not tested this myself) - Downgrading qemu to 2.3 (tested personally, works) - passing -machine pc-i440fx-2.3 to qemu 2.4 (have not tested this myself, I will try that shortly) modules kvm and kvm_intel are loaded and rmmod && modprobing them does not change the situation I have an nvidia card and switching from official binary drivers to nouveau and back does not change the situation. qemu is installed from Arch package. From the PKGBUILD you can see that is is built with the following configuration: ================================================================ export ARFLAGS="rv" export CFLAGS+=' -fPIC' ./configure --prefix=/usr --sysconfdir=/etc --audio-drv-list='pa alsa sdl' \ --python=/usr/bin/python2 --smbd=/usr/bin/smbd \ --enable-docs --libexecdir=/usr/lib/qemu \ --disable-gtk --enable-linux-aio --enable-seccomp \ --enable-spice --localstatedir=/var \ --enable-tpm \ --enable-modules --enable-{rbd,glusterfs,libiscsi,curl} make V=99 ================================================================ cpuinfo on my machine (for the first core only): ================================================================ processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 30 model name : Intel(R) Core(TM) i7 CPU Q 820 @ 1.73GHz stepping : 5 microcode : 0x7 cpu MHz : 1333.000 cache size : 8192 KB physical id : 0 siblings : 8 core id : 0 cpu cores : 4 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 11 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt lahf_lm ida dtherm tpr_shadow vnmi flexpriority ept vpid bugs : bogomips : 3459.21 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual ================================================================ Is there more information I can provide you with to help debug this problem? Thanks, cptG Just confirmed: passing -machine pc-i440fx-2.3 to qemu 2.4 works on my machine, too. I guess I forgot about it before: Kernel version is 4.2.3 OK, I just git-bisected and it found the following commit to probably cause the problem: ===================== SNIP ======================================== 355023f2010c4df619d88a0dd7012b4b9c74c12c is the first bad commit commit 355023f2010c4df619d88a0dd7012b4b9c74c12c Author: Paolo Bonzini