Bhyve: panic: "Unregistered use of FPU in kernel" when starting guest

Neel Natu neelnatu at
Fri Oct 5 04:07:35 UTC 2012

Hi svas,

On Thu, Oct 4, 2012 at 5:58 PM, sree.openwrk <sree.openwrk at> wrote:
> Hi
> I am seeing frequent kernel panic when I try to run the guest OS. I have the
> latest Freebsd (I compiled the latest code from
> svn:// and installed it in my machine).
> While trying to run the pre-built guest provided at
> I get the kernel panic
> (panic: Unregistered use of FPU in kernel)
> I am attaching the core.txt.
> I also want to mention that I was successfully able to boot in to the guest
> OS couple of times. But around 7/10 times I get thsi host kernel panic.
> stack trace:
> vm_run() at vm_run+0xec
> vmmdev_ioctl() at vmmdev_ioctl+0x4ea
> devfs_ioctl_f() at devfs_ioctl_f+0x7a
> kern_ioctl() at kern_ioctl+0xcd
> sys_ioctl() at sys_ioctl+0xfd
> amd64_syscall() at amd64_syscall+0x304
> Xfast_syscall() at Xfast_syscall+0xf7

I am seeing this too but nowhere as frequently as you are. I hit this
last night for the first time and not since.

There hasn't been any change in this part of the code for quite some time now.

Since you can trigger this much more frequently that me, would it be
possible for you to narrow down which change caused this? It would be
hugely helpful.


> regards
> svas

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