FreeBSD in VMware?

Andy Farkas andyf at
Mon Mar 31 20:46:08 PST 2003

On Mon, 31 Mar 2003, james wrote:

> Does anyone have experience running FreeBSD under VMware? My host OS is WinXP
> SP1, running VMware 3.2.
> I'm trying to buildworld (5.0-CURRENT as of today) but the virtual machine just
> gets slower and slower. When I'm monitoring the stats using top, I notice that
> the CPU is spending ~50% of it's time in interrupt. If I Ctrl-C the procedure,
> the load goes down, but interrupt % stays around 20-25% and the system is still
> slow, even though it's not doing anything!

/sys/i386/conf/NOTES says:

# CPU_DISABLE_CMPXCHG disables the CMPXCHG instruction on > i386 IA32
# machines.  VmWare seems to emulate this instruction poorly, causing
# the guest OS to run very slowly.

So, you'll need to rebuild a new kernel on another system with:

options         CPU_DISABLE_CMPXCHG

and copy it into the virtual machine in order to boot normally.


 :{ andyf at

        Andy Farkas
    System Administrator
   Speednet Communications

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