Re: [Qemu-devel] Merging improvements from VirtualBox OSE into qemu?

[Liraz Siri]

Paul Brook wrote:

> You need root privileges to load the random kernel modules required to d 
> this. 
> Not going to happen for qemu.

There's at least one counter-precedent. qemu takes advantage of kqemu
which is also a "random kernel module". How would supporting a kernel
module that simplified a bridged networking be any different?

Also, qemu seems to require root privileges to setup tap devices, so it
wouldn't be a first.

BTW, we don't need this for our own use. We setup VDE + tap devices
bridged to the network interface. Works great, at least for NICs that
support bridging. Also it doesn't require root privileges, only
permissions to connect to the unix socket vde is listening on.
Unfortunately, for most users setting something like this up would
probably be a challenge.

It would be beneficial if qemu supported an easier way to set this up  -
like VirtualBox.

>> 2) improved support for running 64bit guests on 32bit hosts
>>
>>    On my Intel Core 2.4 rig I booted the Debian Lenny live CD in 48
>>    seconds.
>>
>>    By contrast, I booted the same CD under qemu-system-x86_64 in
>>    257 seconds, or 5 times slower...
> 
> You're comparing apples to oranges. Virtualbox uses virtualization, qemu use 
> emulation. I suspect if you boot a 64-bit OS you'll find things significantly 
> slower.

Sorry if I wasn't clear. I am booting a 64-bit OS. I tested booting an
amd64 Lenny live CD and an amd64 Ubuntu hardy desktop. My hardware
supports 64bits but I'm still using a 32bit operating system.

I don't really understand the implementation VirtualBox uses to
accomplish running 64bit VM guests on a 32bit host. Is it possible
VirtualBox have figured out how to run 64bit instructions on a host
running in 32bit mode? (otherwise they'll need to be doing some kind of
emulation)

Testing this VirtualBox feature on hardware that doesn't support 64bit
instructions will be revealing...

> If you're running a 32-bit operating system on a 64-bit machine I'm 
> completely 
> uninterested. Run a proper operating system that actually supports your 
> hardware.

That's your choice, but keep in mind there are many types of users who
have to work under different conditions...

> Not quite true. IIRC VirtualBox is released under a proprietary licence, with 
> some parts dual licenced as GPL. QEMU is a mixture of GPL, LGPL and BSD. This 
> discrepancy tends to disourage cooperation.

According to their website VirtualBox OSE (the opensource edition) is in
fact licensed under the GPL.

Cheers,
Liraz