[Qemu-devel] Trying to emulate an openmosix cluster

[Qemu-devel] Trying to emulate an openmosix cluster

[Christian MICHON]

Hi,

my host is winXPpro, with TAP-win32 drivers. I installed 2
TAP and openvpn. Only one tap can do ICS (internet
connection share) at a time (this is unfortunately needed
for dhcp??).

Guests are openmosix linux nodes done by:
http://www.purehacking.com/chaos/iso/chaos-1.6.iso

I'm using qemu-0.7.1 with tap precompiled for win32.
I read on the originating webpage that only one qemu
can connect to one TAP.

Right now I'm doing 2 instances of qemu with each 1 tap
enabled and of course 2 different macadr.

They boot fine (I need to switch ICS manually to the next
tap otherwise dhcp doesn't start in the 2nd guest).

Yet, they do not see each other. I've 3 questions:

- is it possible in XP hosts to have 2 qemu guests connected
to taps and in network with the host and each other ?

- what would be the proper way to configure openvpn/tap ?

- Is there a way to get both tap to do ICS transparently ?

Thanks in advance
--
Christian

[Qemu-devel] Re: Trying to emulate an openmosix cluster

[Christian MICHON]

I managed doing this simulation using Parallels Workstation
(I'm not trying to spam the list here...).

It worked flawlessly, using bridged networking on a dedicated
TAP-like network device...

My point is the following: today 2 qemu guests with dedicated
macaddr cannot share the same TAP-win32 v8 adapter.

The software I mentionned above doesn't have similar limitation.
Would it be feasible to change the current tap/win32 patch to
overcome qemu's current limitation, and where to start ?

Christian

On 9/22/05, Christian MICHON <christian.michon@gmail.com> wrote:
(...)
> Guests are openmosix linux nodes done by:
> http://www.purehacking.com/chaos/iso/chaos-1.6.iso
(...)

Re: [Qemu-devel] Re: Trying to emulate an openmosix cluster

[Jim C. Brown]

On Wed, Sep 28, 2005 at 09:31:54PM +0200, Christian MICHON wrote:
> My point is the following: today 2 qemu guests with dedicated
> macaddr cannot share the same TAP-win32 v8 adapter.
> 
> The software I mentionned above doesn't have similar limitation.
> Would it be feasible to change the current tap/win32 patch to
> overcome qemu's current limitation, and where to start ?
> 
> Christian
> 

IIRC the limitation is due to the OpenTap implementation of Windows itself.
And thats probably a limitation inherited from elsewhere - the winpcap that
Tap/win32 uses, if I understand correctly.

Of course I can imagine one possibility. Basicially, use something akin to VDE:
a master program is connected several instances of a modified qemu, so that qemu
gets its ethernet packets from the master program and sends its own back to it.
THe master program just does what vde_switch does: shuttle packets between the
different qemu instances. Then you just need to get the master program to use
winpcap or tap/win32 to be able to forward packets between the Windows host and
the qemu guests.

Nothing like that exists right now (at least nothing that I know of) for Windows
- you will need to a) write it from scratch or b) port VDE to Windows.

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.