Rusty Russell's lguest was recently merged into the upcoming 2.6.23 Linux kernel. The merge comment describes the project, "lguest is a simple hypervisor for Linux on Linux. Unlike kvm it doesn't need VT/SVM hardware. Unlike Xen it's simply 'modprobe and go'. Unlike both, it's 5000 lines and self-contained." The comment goes on to note:
"Performance is ok, but not great (-30% on kernel compile). But given its hackability, I expect this to improve, along with the paravirt_ops code which it supplies a complete example for. There's also a 64-bit version being worked on and other craziness.
"But most of all, lguest is awesome fun! Too much of the kernel is a big ball of hair. lguest is simple enough to dive into and hack, plus has some warts which scream 'fork me!'."
The lguest patches are written and maintained by Rusty Russell who explains, "lguest is designed to be a minimal hypervisor for the Linux kernel, for Linux developers and users to experiment with virtualization with the minimum of complexity. Nonetheless, it should have sufficient features to make it useful for specific tasks, and, of course, you are encouraged to fork and enhance it." In the FAQ, lguest is compared to kvm, "kvm requires hardware virtualization support (most recent Intel and AMD chips have it), but it can run almost any Operating System (since it does full virtualization. It also has 64-bit support. Lguest doesn't do full virtualization: it only runs a Linux kernel with lguest support." The FAQ also compares lguest to Xen, "Xen is similar, in that it doesn't need hardware virtualization support (although it can use it), but Xen supports an extensive range of features such as PAE (ie. lots of memory), SMP guests, 64-bit. You have to boot your kernel under the Xen hypervisor; you can't simply modprobe when you want to create a guest."
LWN posted an article about lguest in January titled, "an introduction to lguest" which offers additional details about the lguest implementation.
The commit diffs:
"fork me"
I ain't forking no code with warts! Might catch something.
UML?
And how does lguest compare to User-Mode-Linux? (which is also a Linux-on-Linux solution which needs no modern hardware or a hypervisor)
i may be way of mark, but
i may be way of mark, but the UML do not make the kernel think its running directly on the hardware, but the lguest behaves like a virtualization system.
hmm, i wonder, can it manage to freeze the state of the guest system? and if so, how hard would it be to build some systems around it that loads the guest from a usb stick so that you can in theory bring your desktop with you and not even requiring to reboot?
RTFFAQ :)
http://lguest.ozlabs.org/faq.html
OpenVZ
Any plans for merge OpenVZ into the Linux kernel in a future?
OpenVZ
I would like that very much. In my opinion, there's too much focus on full virtualization, when OS level virtualization is much more useful.
How about linux-vserver
How about linux-vserver ?
Any plan to merge it ?