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Introducing Qubes OS

theinvisiblethings.blogspot.com

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Re: Introducing Qubes OS

#11

Post by [deleted] »

arethuza wrote: post #4
nzmsv wrote: post #3

I think there will be more projects like this. Apps running in a sandbox, thinking they have the OS to themselves. The next logical step is to have all new apps written in managed code, and use virtualization for the "legacy" native code. Come to think of it, isn't it supposed to be the purpose of an operating system: letting programs think they own the hardware? Now they can pretend to own the OS too :) I think we'l…

Presumably that would mean that operating systems (at least for guests) could become a lot simpler as in most cases the guest is there for one specialized purpose and doesn't need most of the features usually found in an OS.

[deleted]

Re: Introducing Qubes OS

#12

Post by plesn »

nzmsv wrote: post #3

I think there will be more projects like this. Apps running in a sandbox, thinking they have the OS to themselves. The next logical step is to have all new apps written in managed code, and use virtualization for the "legacy" native code. Come to think of it, isn't it supposed to be the purpose of an operating system: letting programs think they own the hardware? Now they can pretend to own the OS too :) I think we'l…

Could someone point me at a clear explanation of the difference between a micro-kernel and an hypervisor?

Maybe I need to see something like the Xen presentation at Fosdem again.

Edit: http://www.ok-labs.com/blog/entry/microkernels-vs-hypervisor... is quite ok.

Re: Introducing Qubes OS

#14

Post by AndrewDucker »

plesn wrote: post #12
nzmsv wrote: post #3

I think there will be more projects like this. Apps running in a sandbox, thinking they have the OS to themselves. The next logical step is to have all new apps written in managed code, and use virtualization for the "legacy" native code. Come to think of it, isn't it supposed to be the purpose of an operating system: letting programs think they own the hardware? Now they can pretend to own the OS too :) I think we'l…

Could someone point me at a clear explanation of the difference between a micro-kernel and an hypervisor? Maybe I need to see something like the Xen presentation at Fosdem again. Edit: http://www.ok-labs.com/blog/entry/microkernels-vs-hypervisor... is quite ok.

I'm not an expert, but I'll give it a try.

A hypervisor runs multiple Operating Systems, having each one think that it has access to the whole of the hardware.

A microkernel is one way of writing the kernel of the Operating System, so that each part of it is a separate process, routing messages to each other in a safe manner to get things done, rather than doing direct calls to each others code.

With a hypervisor you wouldn't expect each of the OSes to have any communication with each other at all, whereas with a microkernel you'd expect the different processes to talk to each other a lot.

You can, apparently, repurpose a microkernel as a hypervisor, but I don't know anything about that at all. Presumably the infrastructure is quite similar.

Re: Introducing Qubes OS

#16

Post by gaius »

AndrewDucker wrote: post #14
plesn wrote: post #12

Earlier quoted context omitted.

Could someone point me at a clear explanation of the difference between a micro-kernel and an hypervisor? Maybe I need to see something like the Xen presentation at Fosdem again. Edit: http://www.ok-labs.com/blog/entry/microkernels-vs-hypervisor... is quite ok.

I'm not an expert, but I'll give it a try. A hypervisor runs multiple Operating Systems, having each one think that it has access to the whole of the hardware. A microkernel is one way of writing the kernel of the Operating System, so that each part of it is a separate process, routing messages to each other in a safe manner to get things done, rather than doing direct calls to each others code. With a hypervisor you…

Yes, the Mach microkernel can host multiple OSs. In practice this is rarely done.

Re: Introducing Qubes OS

#17

Post by kmavm »

plesn wrote: post #12
nzmsv wrote: post #3

I think there will be more projects like this. Apps running in a sandbox, thinking they have the OS to themselves. The next logical step is to have all new apps written in managed code, and use virtualization for the "legacy" native code. Come to think of it, isn't it supposed to be the purpose of an operating system: letting programs think they own the hardware? Now they can pretend to own the OS too :) I think we'l…

Could someone point me at a clear explanation of the difference between a micro-kernel and an hypervisor? Maybe I need to see something like the Xen presentation at Fosdem again. Edit: http://www.ok-labs.com/blog/entry/microkernels-vs-hypervisor... is quite ok.

The distinction has never been well-posed, in my opinion. I wrote about it (gulp) almost five years ago here:

http://x86vmm.blogspot.com/2005/11/xen-and-redhat.html

Both present "virtual machines" to client code. For that matter, so does UNIX, although the UNIX virtual machine has some very complex virtual instructions, like fork(2), exec(2), dup(2), etc. You can crudely map most software platforms on a continuum of abstraction, with something like Python's implicit virtual machine (which is dynamically typed and bound late) at one extreme, and a bare-metal VMM whose interface is identical to that of the underlying hardware at the other.

Both paravirtual hypervisors and microkernels extend the underlying hardware, and they do so at a lower level of abstraction than what we call an OS. In practice, the hypervisors extensions feel more like hardware (they might include device models, virtual memory translation, and interrupt models), while the microkernel's would feel more like software (providing RPC mechanisms, security models, abstractions like "thread" and "process", etc.).

Even in practice the line is grey sometimes. L4 used to call itself a microkernel; now it calls itself a hypervisor.

Re: Introducing Qubes OS

#18

Post by soren »

AndrewDucker wrote: post #14
plesn wrote: post #12

Earlier quoted context omitted.

Could someone point me at a clear explanation of the difference between a micro-kernel and an hypervisor? Maybe I need to see something like the Xen presentation at Fosdem again. Edit: http://www.ok-labs.com/blog/entry/microkernels-vs-hypervisor... is quite ok.

I'm not an expert, but I'll give it a try. A hypervisor runs multiple Operating Systems, having each one think that it has access to the whole of the hardware. A microkernel is one way of writing the kernel of the Operating System, so that each part of it is a separate process, routing messages to each other in a safe manner to get things done, rather than doing direct calls to each others code. With a hypervisor you…

An example for a microkernel running a Linux OS is L4Linux (http://os.inf.tu-dresden.de/L4/LinuxOnL4/overview.shtml).

There is a lot of controversy about the distinction between VMMs and microkernels. A view from the microkernel side is given in http://www.ertos.nicta.com.au/publications/papers/Heiser_UL_...

Re: Introducing Qubes OS

#19

Post by soren »

Similar work was done in the OpenTC project (http://www.opentc.net), i.e., running legacy OSs in isolated compartments and multiplex their visual interfaces using a "secure GUI", which labels the windows/interfaces according to certain properties. It also supported OpenGL in the "AppVMs", which is currently omitted in Qubes OS.

The isolation of drivers in separate VMs and enforced isolation using VT-d is definitely interesting. A paper on the disaggregation of dom0 for improved security is http://www.xen.org/files/xensummit_fall07/22_DerekMurray.pdf

Re: Introducing Qubes OS

#20

Post by stcredzero »

gaius wrote: post #15
gosub wrote: post #7

"All problems in computer science can be solved by another level of indirection"

Except the problem of too many levels of indirection.

Actually, that one too. Just hide the levels of indirection. Now you have the problem of complex hidden levels of indirection. (Cheating with one's definition of "solved.")
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