llvm dev - Sep 2006 - [LLVMdev] LLVM based Virtual Machine "Environment" idea sanity check.

I've got an idea for a program, and after readig about 1/3 of your 
documentation, I think LLVM is what I'm looking for.

What I'd like now is some help to see if my idea is "sane" and and
shed
light and direction that could be provided.

I want to build a simplified "Virtual Machine" containing:

A Terminal
Hard Drives (image files)
Some Kind Of Networking Device

LLVM programs would be run "inside" this Virtual Machine, accessing
the
terminal and hard drive images and networking device... but not having 
access to ANYTHING on the host computer (except through the "virtual" 
devices).

I had originally planned on writing my own "processor core" for this 
project... but I'd rather use LLVM (Mainly because I don't have to write
my own high level tools).

Here's what I'm thinking I need to do.  It seems to me that I have to 
"port" LLVM using the System Library to my "Virtual Machine"
(which also
includes a bit of magic of the "Exokernel" operating system stuff). 
Then I can run LLVM programs in my "port" on my
"environment" to get
what I want.

Then LLVM can JIT compile programs but still only have access to my 
"Virtual Machine."  I think.

Any pointers on where to read, Ideas to move on... would be much 
appreciated.

Thanks.


-- 
   +----+       Shawn Boles        +------+/
  /(  )/|     "Chief Engineer"     |     \/
+----+ +      AutoDMC Labs        |Cert. |
|oooo|/                           |Video |
+----+   autodmc at autodmclabs.com  +------+

Hi Shawn,

The idea reminds me a lot on the research on Java operating systems. If
you google for it, you'll find a plenty of references.

In my opinion, the main problem you're going to run into if you want to
design a serious system is interprocess communication. With Java, that's
a huge problem, because each app traditionally runs in a separate virtual
machine. Garbage collection complicates this even further.

You might also want to check Singularity project:
http://research.microsoft.com/os/singularity/

--
    Domagoj


On 9/5/06, Shawn AutoDMC Boles <autodmc at autodmclabs.com>
wrote:
> I've got an idea for a program, and after readig about 1/3 of your
> documentation, I think LLVM is what I'm looking for.
>
> What I'd like now is some help to see if my idea is "sane"
and and shed
> light and direction that could be provided.
>
> I want to build a simplified "Virtual Machine" containing:
>
> A Terminal
> Hard Drives (image files)
> Some Kind Of Networking Device
>
> LLVM programs would be run "inside" this Virtual Machine,
accessing the
> terminal and hard drive images and networking device... but not having
> access to ANYTHING on the host computer (except through the
"virtual"
> devices).
>
> I had originally planned on writing my own "processor core" for
this
> project... but I'd rather use LLVM (Mainly because I don't have to
write
> my own high level tools).
>
> Here's what I'm thinking I need to do.  It seems to me that I have
to
> "port" LLVM using the System Library to my "Virtual
Machine" (which also
> includes a bit of magic of the "Exokernel" operating system
stuff).
> Then I can run LLVM programs in my "port" on my
"environment" to get
> what I want.
>
> Then LLVM can JIT compile programs but still only have access to my
> "Virtual Machine."  I think.
>
> Any pointers on where to read, Ideas to move on... would be much
> appreciated.
>
> Thanks.
>
>
> --
>    +----+       Shawn Boles        +------+/
>   /(  )/|     "Chief Engineer"     |     \/
> +----+ +      AutoDMC Labs        |Cert. |
> |oooo|/                           |Video |
> +----+   autodmc at autodmclabs.com  +------+
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Shawn "AutoDMC" Boles wrote:
> I've got an idea for a program, and after readig about 1/3 of your 
> documentation, I think LLVM is what I'm looking for.
>
> What I'd like now is some help to see if my idea is "sane"
and and shed
> light and direction that could be provided.
>
> I want to build a simplified "Virtual Machine" containing:
>
> A Terminal
> Hard Drives (image files)
> Some Kind Of Networking Device
>
> LLVM programs would be run "inside" this Virtual Machine,
accessing the
> terminal and hard drive images and networking device... but not having 
> access to ANYTHING on the host computer (except through the
"virtual"
> devices).
>   
If you don't mind my asking, can you tell us a little more about your 
overall goal for this project?  How stringent is your isolation 
requirement?  What types of programs do you want to run on this VM 
(programs written in a special language, small C applications, a full 
operating system like Xen/VMWare, etc)?  LLVM can probably make 
development go faster, but the sanity of your project greatly depends on 
what it is for and just how much it will do.
> I had originally planned on writing my own "processor core" for
this
> project... but I'd rather use LLVM (Mainly because I don't have to
write
> my own high level tools).
>   
I think LLVM would probably make a good "processor core" for the very 
reasons you mention.
> Here's what I'm thinking I need to do.  It seems to me that I have
to
> "port" LLVM using the System Library to my "Virtual
Machine" (which also
> includes a bit of magic of the "Exokernel" operating system
stuff).
> Then I can run LLVM programs in my "port" on my
"environment" to get
> what I want.
>   
This doesn't make sense to me.  If you're going to build your virtual 
machine out of LLVM components, why would you make those components run 
on the virtual machine itself?
> Then LLVM can JIT compile programs but still only have access to my 
> "Virtual Machine."  I think.
>   
The difficulty of this depends on the scope of your virtual machine.  
Unlike other bytecode languages, LLVM can represent programs with buffer 
overruns and type unsafe casts, both of which could undermine any 
restrictions that your VM places on programs that it runs.

Now, you could use LLVM to build a safe virtual machine, but you would 
have to figure out how to solve these problems. There are various 
solutions of varying degrees of sanity, but I can't really give any 
feedback on which is more appropriate until I know more about the 
constraints of your project.

-- John T.
> Any pointers on where to read, Ideas to move on... would be much 
> appreciated.
>
> Thanks.
>
>
>

> If you don't mind my asking, can you tell us a little more about your 
> overall goal for this project?
 > Snip
 > I can't really give any
> feedback on which is more appropriate until I know more about the 
> constraints of your project.
> 
> -- John T.
Hopefully I can explain my project more fully (without being too wordy):


"CRAZY CRACKPOT IDEA"

What I want to do is create an idealized "processing node."  This 
virtual machine would include:

1) A processing core
2) Access to "permanent storage"
3) Access to a "Network device"

With any luck, you should be able to run this virtual "processing
node"
on an old Pentium II, on a Apple G3, on a soon-to-be-extinct PS2 
(because everyone'll be selling them to get the PS3), on a Gumstix 
Waysmall computer... basically anything that you can get your hands on.

Each of the computers above would run the "idealized processing node"
in
their native operating system.

An outside observer would see a group of heterogeneous computers 
networked with each other through the internet.

An "inside" observer would see a group of homogeneous "processing
nodes"
networked with each other through Jabber (see below).


"WHAT I WANT TO USE"

I'd like to use LLVM for the Processing Core part of this "idealized 
processing node."  This would allow me to exploit the programming 
language frontends available and the optimizing and JIT compiling 
abilities on the backend.  The key here is that the "node operator" 
might want to help a project, but might not want to fully trust the code 
for the project.  For example, if I run Folding at home, I have to fully 
trust the programmers of the Folding at home client... trust that they 
haven't hidden something evil in their program, or have a hidden 
vulnerability that hurts me.

However, if the Folding at home process was running in a virtual machine, 
they could run just about any code they wanted in it, without me having 
to worry (in general).  Of course, this is where JIT compiling should 
help out...  Basically, the process should have access to the computing 
abilities of the host... but no access to any of the hosts actual 
hardware devices.  As far as this hypothetical Folding at home process is 
concerned... it's running directly on a simple LLVM processor with a 
hard drive and a NIC... that's it.

Also, the Folding at home team has to be able to handle multiple operating 
system's way of handling files and permissions.  My "processing
node"
would give them a complete "raw hard drive" that they could write to, 
without worrying about permissions.  They could use whatever data 
storage scheme they found useful, and I would know that no matter what 
they wrote, they couldn't clobber any of MY data.  Worst case, their 
hard drive image could fill my physical hard drive... but that can be 
remedied in the somewhat harsh but forceful way of killing the offending 
process and deleting their hard drive image.

As for Networking... I was thinking of using something high level, like 
Jabber.  While Jabber was designed for instant messenging... it could 
easily be used for "interprocess communication."  The hypothetical 
Folding at home client would contact "ProjectManager at
foldingathome.org" to
get it's data.  The processing node's "Jabber ID" would be
something
like "node at domain/foldingathome".  The server could send updates to
the
node, and the node could send updates to the server... all without 
worrying about "IP addresses."


The general all around idea *from the user's side* is to make a way for 
a node to be able to run trusted/untrusted code as fast as possible in 
as safe a way as possible.

The general all around idea *from the project developer's side* is to 
have a system that allows the developer to write one version of a client 
and run it on as many "virtual processing nodes" as possible.

The general all around idea *from the point of view of the program being 
run* is that it's the only process running on top of very simple 
"hardware"... a LLVM processor, a hard drive, and a NIC that speaks
Jabber.

My goal is to write the blank-slate VM that is as simple and powerful as 
possible... and let the application writers string the "processing 
nodes" up how they want.  If they want a more complex Interprocess 
Communication... they can write it on top of the 
plain-text-through-Jabber protocol (maybe with XML or YAML or something 
even more exciting).  Or they can write a library that makes a full UNIX 
style file system on top of my raw-block "hard drive."  They can make 
the nodes run single file or in a tree or any way they want... I'm just 
building the "hardware platform."

As for the "processing node" itself... the user can kill it, or
restart
it if it seems to have become "hung..." or the server requesting the 
processing job could ask to have it's job reset or killed.  The most 
important thing is that a badly written program can "nuke" and
"crash"
the VM, but it shouldn't "nuke" or "crash" the host
computer.

This is where I'm stumped... how can I use LLVM inside my "simplified 
processing node," allowing it only access to my "virtual
devices,"
getting it to run "as fast as possible" with as little possibility of
it
clobbering the host computer should something untoward happen to the 
LLVM code?  I'm still sifting through the documentation and feel like 
I'm 90% there to understanding out LLVM works as a Virtual Machine, and 
not a Compiler backend or Intermediate Language.  Or, if LLVM isn't my 
"perfect match," where should I look?

-- 
   +----+       Shawn Boles        +------+/
  /(  )/|     "Chief Engineer"     |     \/
+----+ +      AutoDMC Labs        |Cert. |
|oooo|/                           |Video |
+----+   autodmc at autodmclabs.com  +------+