For new features, I recently updated qemu-kvm 1.5.3 to qemu 2.5.0, but I saw several qemu binaries, /usr/local/bin/qemu-x86_64 and /usr/local/bin/qemu-system-x86_64. It seems qemu-system-x86_64 is the emulator program, since libvirt won't recognize qemu-x86_64. Then what's qemu-x86_64 for?

And according to this qemu doc:

qemu-kvm fork for x86 (deprecated, use upstream QEMU now)

It seems qemu is replacing qemu-kvm. But if qemu not qemu-kvm is used, is the guest CPU still provided by KVM? If not so, will the performance be worse?

  • 1
    On what Linux distribution? – Michael Hampton Mar 31 '16 at 3:20
  • @MichaelHampton Linux 3.10.0-327.el7.x86_64 CentOS 7.1 – dotslashlu Mar 31 '16 at 3:33
  • @MichaelHampton qemu-kvm is not even located in /usr/bin, it's located in /usr/libexec and is binary: /usr/libexec/qemu-kvm: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, stripped – dotslashlu Mar 31 '16 at 6:12

I asked the mailing list, here's what I got:

  • qemu-arch like /usr/local/bin/qemu-x86_64 is for running a program of that arch on the host machine of what ever arch, but not a virtual machine
  • qemu-system-arch like /usr/local/bin/qemu-system-x86_64 is for running a system of that arch on the host machine
  • to enable kvm support, qemu parameter -enable-kvm is needed, libvirt should have taken care of this if right xml is configured

Thanks Jakob for the answer in the mailing list.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.