5 ms·

Why would you use QEMU over virtualbox? (Serious question)

couradical 13y ago
Running headless virtualization on a server with KVM? Sure, for a desktop system it might make sense, but headless systems might be better served with QEMU-KVM.
- uulbiy 13y ago
  Actually you can run virtualbox in a headless server using the VBoxManage and VBoxHeadless[1]. I have been using that for years. [1]: http://www.virtualbox.org/manual/ch07.html http://www.virtualbox.org/manual/ch07.html
kbenson 13y ago
My understanding is that portions of QEMU are used in KVM and Xen, so advancements here enhance those projects as well.
- evol262 13y ago
  This is the correct answer. qemu --accelerator=kvm is the principal way KVM is used.
octopus 13y ago
QEMU lets you emulate ARM architecture on x86 for example, which is not possible with VirtualBox. I've played with a Raspbian image running on QEMU hosted on Windows 7 a few months ago.
- uulbiy 13y ago
  I think this is closest to the correct answer, so I will try to expand on it. Qemu, is a processor emulator[1] and can emulate processors like x86, x86_64, ppc, mips, arm etc. Qemu is usually run with kvm[2]. [1]: http://wiki.qemu.org/download/qemu-doc.html#Introduction http://wiki.qemu.org/download/qemu-doc.html#Introduction [2]: http://www.linux-kvm.org/page/Main_Page http://www.linux-kvm.org/page/Main_Page
- alok-g 13y ago
  How fast does it run as compared to on Raspberry Pi itself?
rainforest 13y ago
In addition to KVM use couradical points out, it's also used in the Bitblaze BAP tool's TEMU component[1], which does dynamic analysis (including taint tracking) over x86 programs and kernels. [1] http://bitblaze.cs.berkeley.edu/temu.html http://bitblaze.cs.berkeley.edu/temu.html
chjj 13y ago
The VirtualBox virtualization drivers have serious issues. They're written so poorly that they're notorious for causing kernel panics on linux. The kernel devs consider your kernel tainted if you load the virtualbox modules. I've crashed so hard using virtualbox that I didn't even get a kernel panic, just a box that wouldn't even respond to alt+sysrq. On top of this, I personally prefer QEMU because it doesn't come with a clunky GUI.
- octopus 13y ago
  To be fair, VirtualBox runs flawlessly on OSX and Windows. I've also used VirtualBox without problems on Ubuntu. What Linux distribution you use ?
  - gtaylor 13y ago
    I've had Ubuntu 12.04 guests crash hard (like the commenter mentioned) on OSX and Linux hosts with VirtualBox.
    - octopus 13y ago
      Probably has something to do with the 3D acceleration Unity needs. In my case (MacBook Air 2013 with 8GB of RAM I run Ubuntu 12.04.4 without a problem).
      - gtaylor 13y ago
        My installs are headless, no 3D accel or Unity needed. As originally mentioned, the VBox kernel modules are of poor quality. You may or may not trigger an edge case in your daily use, with or without a desktop environment.
      - raverbashing 13y ago
        This also may happen if you have another virtualization driver installed (even kvm)
  - chjj 13y ago
CSDude 13y ago
Virt-manager uses QEMU and I think it is pretty good, and much faster than Virtualbox. If you wish to use a desktop though, you should configure the video card of VM manually, its performance is not that good, but if you really want to use desktop VM, I suggest VMWare, I found the interaction much faster, but Virtualbox is pretty good to. In short, QEMU with KVM is way faster, for servers, non-gui interactions.
duaneb 13y ago
It runs non-x86 binaries.
LukeShu 13y ago
There are several reasons I can think of: 1. Qemu supports more architectures, such as running ARM or MIPS code on x86 hardware. 2. Server use. It works with KVM, Xen, Virt-manager, etc; it plays nice with the ecosystem on GNU/Linux. I know my VPS is using Qemu as part of their stack. 3. That last point also means that improvements to KVM and whatnot also improve Qemu. 4. If you are a "freetard", these days VirtualBox uses non-free code in the BIOS. Qemu can be used totally free. 5. As petty as it sounds: It was around first, and people stick with what they know (this is the principle reason I use Qemu).
- thristian 13y ago
  Actually, VirtualBox's BIOS code is 100% freely redistributable and modifiable. Unfortunately, the only compiler capable of building it is non-Free (OpenWatcom). It turns out there's not a whole lot of interest in writing compilers targeting 8086 real mode these days. :(
  - LukeShu 13y ago
    Oops, you are correct. Good catch! That is also the compiler required for FreeDOS; an effort towards creating a free replacement would be helping multiple projects.
dice 13y ago
QEMU/KVM are the default virtualization used in OpenStack [1], for one. I also use it on my laptop to host guests because of how much Virtual Box sucks under Linux [2], as others have mentioned. [1] https://www.openstack.org/ https://www.openstack.org/ [2] https://lkml.org/lkml/2011/10/6/317 https://lkml.org/lkml/2011/10/6/317
venomsnake 13y ago
VGA Passtrough
jsight 13y ago
The best reason, IMO, is that the tools around KVM (using QEMU) and virt-manager are becoming much more pleasant to use than their VirtualBox counterparts. The GUI could still use some cleaning up, IMO, but overall I have found the experience much more pleasant in recent virt-manager releases than the VirtualBox way of doing things.

Running headless virtualization on a server with KVM? Sure, for a desktop system it might make sense, but headless systems might be better served with QEMU-KVM.

uulbiy 13y ago
Actually you can run virtualbox in a headless server using the VBoxManage and VBoxHeadless[1]. I have been using that for years. [1]: http://www.virtualbox.org/manual/ch07.html http://www.virtualbox.org/manual/ch07.html

kbenson 13y ago

My understanding is that portions of QEMU are used in KVM and Xen, so advancements here enhance those projects as well.

evol262 13y ago
This is the correct answer. qemu --accelerator=kvm is the principal way KVM is used.

octopus 13y ago

QEMU lets you emulate ARM architecture on x86 for example, which is not possible with VirtualBox. I've played with a Raspbian image running on QEMU hosted on Windows 7 a few months ago.

uulbiy 13y ago
I think this is closest to the correct answer, so I will try to expand on it. Qemu, is a processor emulator[1] and can emulate processors like x86, x86_64, ppc, mips, arm etc. Qemu is usually run with kvm[2]. [1]: http://wiki.qemu.org/download/qemu-doc.html#Introduction http://wiki.qemu.org/download/qemu-doc.html#Introduction [2]: http://www.linux-kvm.org/page/Main_Page http://www.linux-kvm.org/page/Main_Page
alok-g 13y ago
How fast does it run as compared to on Raspberry Pi itself?

rainforest 13y ago

In addition to KVM use couradical points out, it's also used in the Bitblaze BAP tool's TEMU component[1], which does dynamic analysis (including taint tracking) over x86 programs and kernels. [1] http://bitblaze.cs.berkeley.edu/temu.html http://bitblaze.cs.berkeley.edu/temu.html

chjj 13y ago

The VirtualBox virtualization drivers have serious issues. They're written so poorly that they're notorious for causing kernel panics on linux. The kernel devs consider your kernel tainted if you load the virtualbox modules. I've crashed so hard using virtualbox that I didn't even get a kernel panic, just a box that wouldn't even respond to alt+sysrq. On top of this, I personally prefer QEMU because it doesn't come with a clunky GUI.

octopus 13y ago
To be fair, VirtualBox runs flawlessly on OSX and Windows. I've also used VirtualBox without problems on Ubuntu. What Linux distribution you use ?
- gtaylor 13y ago
  I've had Ubuntu 12.04 guests crash hard (like the commenter mentioned) on OSX and Linux hosts with VirtualBox.
  - octopus 13y ago
    Probably has something to do with the 3D acceleration Unity needs. In my case (MacBook Air 2013 with 8GB of RAM I run Ubuntu 12.04.4 without a problem).
    - gtaylor 13y ago
      My installs are headless, no 3D accel or Unity needed. As originally mentioned, the VBox kernel modules are of poor quality. You may or may not trigger an edge case in your daily use, with or without a desktop environment.
    - raverbashing 13y ago
      This also may happen if you have another virtualization driver installed (even kvm)
- chjj 13y ago

CSDude 13y ago

Virt-manager uses QEMU and I think it is pretty good, and much faster than Virtualbox. If you wish to use a desktop though, you should configure the video card of VM manually, its performance is not that good, but if you really want to use desktop VM, I suggest VMWare, I found the interaction much faster, but Virtualbox is pretty good to. In short, QEMU with KVM is way faster, for servers, non-gui interactions.

duaneb 13y ago

It runs non-x86 binaries.

LukeShu 13y ago

There are several reasons I can think of: 1. Qemu supports more architectures, such as running ARM or MIPS code on x86 hardware. 2. Server use. It works with KVM, Xen, Virt-manager, etc; it plays nice with the ecosystem on GNU/Linux. I know my VPS is using Qemu as part of their stack. 3. That last point also means that improvements to KVM and whatnot also improve Qemu. 4. If you are a "freetard", these days VirtualBox uses non-free code in the BIOS. Qemu can be used totally free. 5. As petty as it sounds: It was around first, and people stick with what they know (this is the principle reason I use Qemu).

thristian 13y ago
Actually, VirtualBox's BIOS code is 100% freely redistributable and modifiable. Unfortunately, the only compiler capable of building it is non-Free (OpenWatcom). It turns out there's not a whole lot of interest in writing compilers targeting 8086 real mode these days. :(
- LukeShu 13y ago
  Oops, you are correct. Good catch! That is also the compiler required for FreeDOS; an effort towards creating a free replacement would be helping multiple projects.

dice 13y ago

QEMU/KVM are the default virtualization used in OpenStack [1], for one. I also use it on my laptop to host guests because of how much Virtual Box sucks under Linux [2], as others have mentioned. [1] https://www.openstack.org/ https://www.openstack.org/ [2] https://lkml.org/lkml/2011/10/6/317 https://lkml.org/lkml/2011/10/6/317

venomsnake 13y ago

VGA Passtrough

jsight 13y ago

The best reason, IMO, is that the tools around KVM (using QEMU) and virt-manager are becoming much more pleasant to use than their VirtualBox counterparts. The GUI could still use some cleaning up, IMO, but overall I have found the experience much more pleasant in recent virt-manager releases than the VirtualBox way of doing things.