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Linux Gains Two New Virtualization Solutions
Posted by
CowboyNeal
on Sat Jul 21, 2007 08:51 AM
from the almost-as-good-as-the-real-thing dept.
from the almost-as-good-as-the-real-thing dept.
An anonymous reader writes "The upcoming 2.6.23 kernel has gained two new virtualization solutions. According to KernelTrap, both Xen and lguest have been merged into the mainline kernel. These two virtualization solutions join the already merged KVM, offering Linux multiple ways to run multiple virtual machines each running their own OS."
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So, will it run Windows? (Score:2, Interesting)
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Re:So, will it run Windows? (Score:5, Informative)
You mean Lguest? FTA:
Lguest doesn't do full virtualization: it only runs a Linux kernel with lguest support.
So the answer is no, Lguest does not run Windows. Xen runs Windows, but only if you have a VT-capable processor. Like Lguest, Xen can run Linux without a VT-capable processor.
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Why? (Score:4, Interesting)
I think this will confuse users. Choice is good, yes, but 3 VMs in the kernel? Sounds like overkill.
Re:Why? (Score:5, Insightful)
Don't get me started on buses.. PCI, USB, SCSI, IDE, how many do you need?!
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Re:Why? (Score:4, Informative)
That said, you mentioned KVM.. KVM (for Kernel-based Virtual Machine) is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V). (from here [qumranet.com]). It *is* a hardware driver.
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Re:Why? (Score:4, Interesting)
in this situation the analogy is clear. As time went on, people discovered new designs for virtualization and decided to implement them. Each design has strengths and weaknesses that make them appropriate for different situations. The same is true of hardware buses; older buses tend to be cheaper to implement. There are exceptions, it's probably cheaper (or will soon be cheaper due to economies of scale) to implement PCI-Express at PCI bandwidth than it is to implement PCI itself. It's certainly cheaper to implement firewire than SCSI (in spite of this, there are practically no native firewire storage devices. But anyway.) (And firewire, which goes up to 800MHz which peaks at 100MB/sec, is superior in most ways to anything up to and including LVD SCSI, including speed, simplicity of cabling, etc etc) Can you tell I have an ax to grind?
But anyway, the point is that we have UML, which runs linux as a process; we have this new lguest, which runs linux as a module; we have xen which is full virtualization without a need for VT, we have kvm which is like xen but does need VT, we have vmware which is also pretty much like xen (and doesn't need VT, although I was under the impression newer versions of vmware would take advantage of it if present, for a speed boost.)
There's some other examples too, but these are enough to talk about right now. Suffice to say that each approach has advantages and disadvantages. But they're useful for different things!
For maximum separation, for example, you could have a Linux that ran servers inside of different UML processes. While exploits in UML would still be possible, this would stop a privilege escalation bug in one server from affecting another. I envision a tool that tracks dependencies and generates the UML filesystem images automatically. Syslogging is done through the virtual network, to the syslog on the core system. Want to test a package? A command to run it in a UML might be as simple as running fakeroot. (fakelinux?) You could do all of this with this new lguest system, instead of UML.
Meanwhile, you're still going to need a full virtualization solution to run non-linux operating systems under Linux (at least until a cobsd (see "colinux") comes out - I forgot about that one for a moment) so there's still a purpose for that.
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Re:Why? (Score:5, Funny)
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make xconfig
you can see that the very first option is "code maturity level options", and that there are hundreds of features which are by default NOT TURNED ON and therefore do not show up in "anything resembling a production environment". And I'm not talking about kernel modules here, but things like CONFIG_MATH_EMULATION (under "processor type and features" near the bottom of the page) which
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Only if enabled in the distribution. It doesn't harm anyone to have it available in the kernel source tarball. And both KVM and Lguest are implemented as modules, so if you don't load them, they aren't there.
Could somebody clear this up for us? (Score:5, Insightful)
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Re:Could somebody clear this up for us? (Score:4, Insightful)
As long as N solutions are maintained there will be N solutions in the kernel. A solution won't be dropped because it performs worse.. or any other "technical" reason.
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Very fishy and intriguing (Score:2)
"The happy theme of today's kvm is the significant performance improvements, brought to you by a growing team of developers. I've clocked kbuild at within 25% of native. This release also introduces support for 32-bit Windows Vista. "
I can't understand why the Linux kernel development team had 'Windows Vista support' as one of the items on their agenda at all. Virtualisation as I understand it, is basically an abstraction of the hardware that is performed in software. Should not all operating systems be designed to work with standard instruction sets, interrupts, registers and memory?
Why should it be the job of a particular kernel or it's VM component to satisfy specific requirements of a specific version of another kernel (the Vista k
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Should it not be the other way round - i.e. for closed-source Vista to be compatible and optimised for the open-source Linux kernel?
Y
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The people who work on this stuff really wouldn't call themselves kernel developers, but ok, whatever. Associating any of the VM stuff with Linus is even more retarded.. what they do in their own modules is none of his fault or concern.
I find the announcement about these VMs is from Linus himself. Besides, it is Linus who decides which components get into the main kernel tree, so he is answerable for any decisions made.
Anyway, some people want to run Vista in a VM on Linux. These VM solutions don't try to virtualize every nook and cranny of the x86 hardware. Vista uses the system level x86 hardware in a slightly different way to XP. As such, it takes some changes to make Vista work.
If Vista has any idiosyncracies, it should be the job of the overpaid, bloated development team in Redmond to iron out the kinks and make it standards-compliant. Why should it be a concern of the Linux kernel development team? Besides, how did these developers gain access to quirky behaviour of Vista?
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I find the announcement about these VMs is from Linus himself. Besides, it is Linus who decides which components get into the main kernel tree, so he is answerable for any decisions made.
Linus puts whatever he wants into his tree, yes. His tree is the defacto "main" kernel tree, yes.
If Vista has any idiosyncracies, it should be the job of the overpaid, bloated development team in Redmond to iron out the kinks and make it standards-compliant. Why should it be a concern of the Linux kernel development team? Besides, how did these developers gain access to quirky behaviour of Vista?
What standards are you talking about exactly? The Intel x86 hardware documentation? I can assure you they are writing their code to those "standards" otherwise their code wouldn't work..
If anything the virtualization guys are the ones who are not implementing the "standards".. as not everything that will run on an x86 processor will run the same way under virtualization. That's simply because it's a lot of
Re:Could somebody clear this up for us? (Score:5, Informative)
They each fill very different niches, so there are very good reasons for having all 3 in the kernel.
Parent
As a testament to my lack of knowledge... (Score:2)
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Just like the hardware support for webcams is in the kernel.
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Then there's para-virtualization.. modifying the kernel of the guest OS so you don't even need anything in the kernel. W
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Only one hardware branch of the kernel gets compiled, and yes, I know I can choose not to compile many things into the kernel, and do so whenever I compile it.
See the post below you for an answer that was helpful. Compare that to your answer, and figure out how to answer a question instead of trying to belittle someone.
GPU support question (Score:5, Funny)
The only reason I currently have a windows partition at all is for gaming.
Being able to run Windows 3D games in a VM would allow me to move to a Linux-only box and also give me a nice way of:
* managing the way windows keeps grabbing diskspace
* remove the need to go through reinstalling/reactivating windows every 6 months or so
* limiting the damage Windows virusses can do
* limiting all the phone-home comms with Microsoft that windows keeps doing
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Probably the first thing they'll do is make it so X running in a virtual machine can share the same DRM (Direct Rendering Module) as X running on the host. Of course, that's not much good to a Windows guest.
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So do any of these solutions support 3D graphics (nvidia) hardware?
The only reason I currently have a windows partition at all is for gaming.
I recently read an article on the progress of just this. It sounds pretty cool and the initial results are impressive. This combined with the DX->OpenGL Wine code, that I'm sure will be open sourced from the makers of parallels (just had a slashdot story on this), makes for an exciting future for providing hardware acceleration to guest applications.
More information: http://www.cs.toronto.edu/~andreslc/vmgl/ [toronto.edu]
Clarification of these technologies (Score:5, Informative)
Xen - the Linux kernel supports code allowing it to be run as a guest underneath the Xen kernel, all through software. Linux's support for Xen does not make Linux a virtualization platform, only a GUEST for the Xen kernel which sits at Ring-0. (though a "dom0" Linux system can interact intimately with the Xen kernel, it actually sits at Ring-1). I should note that the Xen kernel also supports hardware virtualized domains, though this is unrelated to the patches to Linux.
KVM - the Linux kernel supports virtualization of guests through hardware extensions, this requires supported hardware. Linux becomes the Ring-0 kernel.
lguest - (my understanding is) an unmodified Linux kernel can act as a hyper-supervisor through loading Linux kernels as modules. Linux sits as both Ring-0 (supervisor) and Ring-1 (guests). This is experimental with limited features and only supports Linux guests.
UML - the Linux kernel becomes a userspace program. This allows Linux to run as an executable application/program. With UML, Linux can be compiled for a Linux or Microsoft Windows target. The executing OS sits at Ring-0 and the UML program sits at Ring-1. This has the advantage of requiring no modifications to the host OS and is very portable (you could email an entire Linux system to a friend without requiring anything installed to their system), but the disadvantage of poor performance.
From a high-level, the products UML, Xen, and lguest are actually very similar in function. They act as architectures to which Linux can be compiled in order to make it a guest OS of another Ring-0 kernel. These architectures provide the targets of a kernel module (lguest), a userspace program (UML), or a xen-domU guest (Xen). On the other hand, KML is the only patch that is intended to add support to Linux to act as a Ring-0 kernel on behalf of guest systems -- and even then, KML can be viewed more as a hardware driver for the processor extensions.
Re:Clarification of these technologies (Score:5, Informative)
The UML program sits at ring-3 on X86 machines: it's just a normal user program using the ptrace() mechanism and extensions [except when the host has been patched with SKAS, but even here it's just a "normal user program". Rumor has it that SKAS might eventually make it into mainline, but it's time in 'real soon now' is starting to rival Duke Nukem Forever's.]. Rings 1 and 2 are odd, rarely used (IIRC there's the current virtualization craze and OS/2 as notable consumers) features of the x86, derived from MULTICS. For processors with only two (user & supervisor) modes, identify ring 0 with supervisor mode and the other rings with user mode.
It is a little odd to say that Linux "becomes" the Ring-0 kernel under KVM. It was already running in ring 0.
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Re:Clarification of these technologies (Score:4, Interesting)
Personally I like the approach of OpenVZ [openvz.org] and VServer [linux-vserver.org] better. The main OS and the guests all share the same kernel, share the RAM and their root filesystems can be just subdirectories of the host's filesystem. When inside the virtual server you don't realize that though. You only see your own processes and everything works as if it was a dedicated server. You can run iptables, reboot and just about everything you could normally do in XEN/KVM/VMWare. Including live migration of virtual servers to other physical hosts. chroot on steroids.
I really hope OpenVZ and/or VServer will be merged at some point. VServer seem to keep up with current kernel releases so that wouldn't be too hard to merge I guess. OpenVZ usually have a lag of something like half a year.
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Wireless card??? WTF? (Score:2)
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If you NAT your VM network traffic, then things work (well sorta, with all the nastiness that NAT comes with).
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This [launchpad.net] is the Ubuntu bug report (note the length and number of duplicates) which actually breaks apt on installation, but it's not Ubuntu specific; you can't configure it manually with this wireless card either. The only solution is to disable networking virtualization, which means I can't even have VMware use my wired connection unless I disable the wireless card entirely or physically remove it fro
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Re:Multiple ways to run Multiple OSs (Score:4, Informative)
I used to work for a search engine company (not Google) that has thousands of linux servers. After doing a bit of research they discovered that the vast majority of these machines are idle for a good amount of time. Rather than buy new servers they simply installed Xen and intellegently divided up the physical hardware to perform their different tasks. Now instead of separate physical servers to do web spidering, data analysis, log processing, etc. they've combined these tasks onto the same physical hardware but kept them as individual virtual servers.
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Solved it three different ways! (Score:2)
Please review Robert Frost: "The Road Not Taken [amandashome.com]".
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So the comparisment with emacs is very inaccurate, emacs is a userland tool, and doesn't have kernel modules
Re:I RTFA twice and thought to myself... (Score:5, Funny)
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Linux + Xen + W2K lets her leave the windows desktop and still use these tools.
Pretty straightforward.
Yes.
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I only have Ubuntu installed and I don't see why a VM is such a massive feature these days?
I have vmware installed and use it on a regular basis. Here's what for:
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