Linux Kernel to Include KVM Virtualization

It looks like the newest version of the Linux kernel (2.6.20) will include KVM, the relatively new virtualization environment. From the article: "Thanks to its approach KVM already runs in the current kernel, without any extensive bouts of patching and compiling being required, after the fairly simple compilation of a module. Virtual machines that run unmodified operating systems are meant to appear in the host as a simple process and work independently of the host kernel. In a fashion comparable to that of Xen a modified QEMU is used for the supportive emulation of typical PC components of the virtual machines."

Comments

how many KVMs

[Gopal.V]

First there was KVM switches and then there was the Java KVM (kilobyte VM).

Now there's the linux KVM which has nothing to do with either those or the Kernel VM rewrites of the linux past.

Leave that acronym alone !

VMWare

[brunes69]

You can do that in VMWare player and VMWare server, both of which are free (as in beer).

http://www.vmware.com/

Re:KVM switch?

[TheThiefMaster]

Don't get me started on belkin, I've had trouble with everything they've made. I've even got a usb bluetooth adapter here that isn't xp sp2 compatible. It's an F8T001_v1, I've had it since before SP2 was released, and I tried it again recently and they still haven't made SP2 drivers for it (last driver release was 2003).

But seriously, I read an article once about why kvms can't switch mice properly, apparently it's because the ps2 mouse protocol has no synchronisation in it. So when a cheap kvm switches the mouse to the other pc, switching in the middle of a data packet more often than not, the pc starts thinking the start of the packet is the middle. This results in things like "moving the mouse clicks the buttons" and other such fun. Most mouse drivers can identify this problem and correct for it, but it takes a few seconds of mouse movement. Even better, some laptops have a kind of ps2 merge circuit for their ps2 touchpad and external mouse, so if the external mouse gets out of sync there is no way to correct it, because the merge is too stupid and the drivers can't see the touchpad and mouse separately, so it can't independently change the synch of the external mouse.

In other words, either get a decent kvm, a kvm that can switch usb mice (which do have synch and so don't have this problem), or stick to two separate mice.

Oh, one more word of kvm warning, they often can't handle resolutions above 1024x768 on the monitor without blurring badly. Whether this is the fault of the cheap cables they always come with or the kvm itself, I don't know.

Virtualisation on Linux

[cortana]

Xen
VMWare
linux-vserver
UML
OpenVZ
Plex86
Qemu
Bochs
lhype

and now

KVM

http://linuxvirtualization.com/ has some good linux to recent announcements regarding virtualisation software on Linux.

Are there any more?

Re:Virtualisation on Linux

[julesh]

Many of these are substantially different from standard virtualization systems, though:

linux-vserver and OpenVZ are chroot-based virtual hosting environments, not virtualized operating systems. You can add OpenVSD to the list of such projects, although it appears to be practically dead.

Qemu and Bochs are PC emulators, not virtual machines, which is a slightly more subtle distinction, but still one that needs to be made.

UML is something different entirely -- an operating system that is designed to run as a process on another operating system with a similar syscall interface.

That leaves KVM, Xen (which uses an exokernel, so is effectively its own OS, not a Linux-hosted VM), VMware (which is proprietary) and plex86 (which will only run modified kernels so doesn't provide a true virtual machine).

So, you see, KVM is effectively the only Linux-based VM system (by the traditional definition) on that list.

Re:Virtualisation on Linux

[Ed Avis]

You left out dosemu (the earliest hardware virtualization, using the V86 mode of all 386-compatible processors - but also supporting 32-bit DPMI applications) and DOSBox (which is based on bochs). Also Cooperative Linux for running a Linux system under other OSes, such as Windows.

Re:Virtualisation on Linux

[baadger]

Actually there is/was an open source effort to replace the KQEMU "accelerator" module... QVM86. Unfortunately it needs work, it's functional but only operates on x86 (no x86_64). There are patches against current CVS for compatibility with KQEMU 1.3.x and QEMU 0.8.2 on the QVM86 newsgroup but development seems to have otherwise stagnated.

Also the author of KQEMU did say he would open up the source if sponsored.

Re:Only up to date processors? How up to date?

[Anonymous Coward]

very.. I believe only the core's / some 'p4' based xeons ..
look for 'intel VT' and 'amd virutalization (pacifica)'
in your chip specs..

if you didn't buy it in the last year or so, most likeley not.

For those brain-dead like me:

[erroneus]

http://www.haifux.org/lectures/152/kvm-external.pd f

This breaks down in fairyly simple terms where KVM fits in. Basically, the approach is pretty close to the VMware approach but presently requires the newer, more advanced processors to operate. So where VMware can run on more hardware such as my Pentium M processor based laptop, KVM will not likely work as far as I can tell. (Please tell me I'm wrong if I am.)

I'm disappointed that I will not be able to play with this new toy any time soon as I don't think I will be buying new hardware any time soon.

Re:For those brain-dead like me:

[erroneus]

http://www.intel.com/products/processor_number/pro c_info_table.pdf

This confirms it. I can't play. But it also lists who can play! Are you on the list? Check it out.

Re:For those brain-dead like me:

[zdzichu]

Yes, it needs processor with Intel VT-x (Vanderpool) or AMD SVM (Pacifica). So Pentium 4/D (available since 2005), most of Core Duos, Core 2 or AMD CPUs sold since August this year (Socket F/1207 and AM2) qualify.

Re:For those brain-dead like me:

[gbjbaanb]

No, KVM will work, but it will not be as fast as you'd like. With the new CPU instructions, it will be a lot faster. (the reason is down to the memory management unit, with a VM every time it context switches, it throws away some cached page state. The new CPUs deal with this so you get the better performance).

I read a ng post where the author said his VM desktop was fine, but with the new CPUs you'd get performance very near running natively.

Re:For those brain-dead like me:

[idlake]

Basically, the approach is pretty close to the VMware approach but presently requires the newer, more advanced processors to operate.

That's not a good way of putting it, because it incorrectly suggests that VMware somehow pioneered virtualization and KVM follows it. But what VMware actually pioneered was a workaround for a lack of virtualization instructions on older x86. Modern x86 virtualization follows models that have been around since long before VMware existed.

Re:Only up to date processors? How up to date?

[d34d.10n]

From Wikipedia:

"Intel VT was officially launched at the Intel Developer Forum Spring 2005. It is available on most Pentium 4 6x2, Pentium D 9x0, Xeon 3xxx/5xxx/7xxx, Core Duo and Core 2 Duo processors. On some implementations, IVT support may be switched off in the BIOS/EFI."

"AMD processors using Socket AM2, Socket S1, and Socket F include AMD Virtualization support. In May 2006, AMD introduced such versions of the Athlon 64 and Turion 64 processors. AMD Virtualization is also supported by release two (x2xx series) of the Opteron processors."

Re:Excellent

[repvik]

Yes:

"The driver supports i386 and x86_64 hosts and guests. All combinations are allowed except x86_64 guest on i386 host. For i386 guests and hosts, both pae and non-pae paging modes are supported." (From LKML)

Re:I hope Windows can't access the hardware.

[Schraegstrichpunkt]

How in the WORLD does access to the video, sound, or any other daughterboard grant access for a virus?

DMA + lack of IOMMU = unrestricted access to system memory

... in the WORLD

Re:VMotion/HA?

[smodak]

Well, the company behind KVM (I realy hope they choose some other name for the finished product) reportedly has Moshe Bar on their payroll. IIRC he is the guy involved in OpenMosix, so I'd think that this facility, if not already available, would be available very soon.

Re:What benefits does this give?

[BokLM]

Why is this comment rated informative ?
For thoses who are interested, look at this page :
http://kvm.sourceforge.net/faq.html

It is the same thing, but it is actually readable.

Re:qemu

[brunes69]

Take off your tinfoil hat and let your head breathe.

You think VMWare tells anything to Microsoft? Why would they? They are about as far from being "in bed" with them as you can imagine. For one, Microsoft is their #1 competitor (with Virtual Server).

You can rest assured that VMWare tells **as little as possible** to Microsoft about everything.

All this is not to mention the fact that what you are implying would be highly unethical and if VMWare actually did that, they would have been found out long ago and publicly flogged. VMWare does not "phone home" to anyone, including VMWare Inc. itself.

Read their FAQ

[Shadowlore]

It says in their FAQ:
"kvm today supports non-live migration, where there is a pause while memory content is transferred. Pauseless live migration is work in progress."

Re:What is the big deal?

[An Onerous Coward]

Running Windows and Linux at the same time is a pretty big deal, if you need access to Windows-only apps. It's good for web developers, who need to check out their results in IE, and it may make some Windows to Linux migration attempts easier (since the migration might otherwise be held up by a desperate need for a single legacy app).

What else does it offer you, the consumer? Well, you can try things that no sane mortal should attempt with their computer. Install crapware and find out what it actually does to your system, and just delete the VM when you're done. Or let your kid loose on your computer knowing that there isn't much he can do to hose it.

Since you ask "what could it possibly offer anyone", I'd also point out that VMs are getting popular on computer farms (web hosting, etc), where clients are allowed to rent a virtual machine with guaranteed access to a certain amount of memory, a certain amount of clock cycles, etc. In clusters, there is also technology for halting a virtual machine on one box, migrating it to another, then starting it running there. That makes it much easier to take down a given box for maintenance.

One other thing you can do is network simulations. You could have a dozen VMs running on a single host, all forming a virtual network of whatever topology you desired. This can be useful for trying out new network protocols and distributed applications.

I'm sure there are lots of other examples that I'm not aware of.