Recommended virtualization technique for debugging/developing FreeBSD

Lawrence Stewart lstewart at
Tue Feb 26 00:12:20 UTC 2008

Hi Peter,

Peter Schuller wrote:
> Hello,
> I was wondering what people use, in the abscense of suitable actual hardware, 
> to debug/develop FreeBSD (the kernel in particular). I'm willing to resort to 
> almost any host, including Windows, as long as I have something reliable.
> I haven't had much luck with qemu (crashes), nor virtualbox (crashes). I was 
> going to go for vmware on Windows, but while it ran FreeBSD pretty well, 
> before I had even percolated the disk layout enough to trigger the bug 
> (required root-on-zfs) I was hoping to trigger, the vmware configuration tool 
> crapped out on me and produced a configuration it could not itself read.
> What do all you regular kernel developers use, if not physical hardware?

Not trying to discount your experiences, but I've had nothing but 
success using Vmware under linux as a FreeBSD development platform. The 
vmware tools take some coercing to work on FreeBSD 7/8, but I've done it 
and they work fine so far.

One thing I will note is that Vmware really messes with the kernel's 
timing and so time dependent behaviour will often manifest itself 
differently in vmware than on real hardware. Race conditions, locking 
problems, etc. are all less likely to show up in Vmware than on real 
hardware in my experience. Definitely not a show stopper, but something 
to be aware of when using it as a dev platform.

I have a step by step build guide which I created when setting up my 
home vmware dev server which I'd be more than happy to share with you if 
you're interested.


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