FreeBSD as VM host OS?

Garrett Cooper youshi10 at
Mon Dec 18 13:52:42 PST 2006

Mario Lobo wrote:
> On Monday 18 December 2006 18:19, Garrett Cooper wrote:
>> Bill Moran wrote:
>>> In response to David Newman <dnewman at>:
>>>> My question is whether FreeBSD is a suitable _host_ OS for any virtual
>>>> machine environment, preferably with support for SMP, amd64, and guest
>>>> OS speed at or close to native hardware speeds.
>>> *) jails provide virtual hosting at native speed, but _only_ for FreeBSD
>>>    guests.  i.e., you can't run Linux in a FreeBSD jail
>>> *) qemu works well on FreeBSD in my experience, but there is a
>>> considerable performance hit.
>>> *) Xen should give you what you want, but I've no information on the
>>>    status of Xen on FreeBSD at this time.
>>> HTH
>> Try qemu. Some people on this list (or maybe other FreeBSD lists--can't
>> remember :P), have reported success in using qemu as the host VM.
>> Xen is a royal pain, even though it is fast. I tried setting it up once
>> under Gentoo and it was trying to load a lot of services at boottime,
>> pulled in custom (Xen) kernel patched sources, etc. Needless to say, the
>> Xen patched kernel sources was the show stopper, because one never knows
>> what in the world the patches may do if installed with other patches.
>> Moreover, the Xen patches may wreak havoc with userland programs (like
>> Linux does on occasion), etc.
>> Just my .02.. qemu has a kernel module, but if you don't feel like
>> tainting the kernel with an alpha feature, their userland(-only) program
>> is fairly stable from what I have read.
>> -Garrett
> I use qemu here. I run a windows XP pro VM and a FEDORA CORE 5 VM, inside a 
> FreeBSD host, with kqemu mod loaded. This make a huge diff in performance.
> The install for both OSes were slow but it's perfectly OK if you take into 
> account the disk emulation and all.
> Besides that, no complains whatsoever !. Native speed ? on a VM ? only in jail 
> ( I think) or dual boot, but qemu comes pretty close. I have them hooked on a 
> bridged network, with sound. and a big plus: no linux emulation required 
> (like vmware, which I tried to try but serial numbers and linux stuff made me 
> give up)
> I hope this helps
Your success with kqemu probably depends on what architecture you are 
running though, because some things may run solid on i386, but x64, ppc, 
sparc(n), etc may not agree with kqemu as much..

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