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 !

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.

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:

[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: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: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.