Re: bhyve vCPU limit

That limitation appears to still exist in FreeBSD 13.0-RELEASE:

[root@grit] # freebsd-version -k ; grep 'VM_MAXCPU' 
/usr/src/sys/amd64/include/vmm.h
13.0-RELEASE
#define	VM_MAXCPU	16			/* maximum virtual cpus */

I ran into this in May 2021 and with some help from folks on this list 
was able to increase it. The simplest (if not minimalist) way to do that 
is:

1. edit /usr/src/sys/amd64/include/vmm.h to increase that value: I used 
48
2. make buildworld
3. make installworld

The increased value has been working fine for me since I did that. I run 
a couple of VMs with 24 vCPUs each and several others with smaller 
numbers all the time and have run others with as many as 48 temporarily. 
No problems that I have seen.

I don't use cbsd so can't comment on that.

On Wed 2021-12-01 04:24 AM MST -0700, <jbo@insane.engineer> wrote:

> Hello folks,
>
> I'm using the sysutils/cbsd port for managing bhyve VMs on multiple 
> hosts.
> CBSD does currently not allow to assign more than 16 vCPU cores to a 
> VM.
> I've reached out to the CBSD author(s) to check up on this situation. 
> I was
> referred to an E-Mail from this mailing list from 2014 at which point 
> this was
> apparently a bhyve limitation.
>
> I'd like to understand whether this limitation is still present to 
> this date. Or
> whether bhyve is able to assign more than 16 vCPU cores to a VM?
>
> Thank you for all your hard work & Best regards,