[1]Bhyve is the BSD hypervisor / virtual machine manager (VMM) developed by FreeBSD that supports a range of operating systems and across CPU vendors. With time Bhyve has also been ported to other BSDs and even Illumos and macOS. The Linux kernel is now in the process of adding guest detection for the Bhyve hypervisor in order to support VMs with 255+ vCPUs.

The Linux kernel hasn't had a reason until now for adding Bhyve detection besides cosmetic/informational reporting purposes until now. But with [2]FreeBSD 15.0 coming out later this year, there's a new technical reason for the Linux kernel needing guest detection of Bhyve: supporting larger VMs.

FreeBSD 15.0 will support 15-bit MSI enlightenment to support more than 255 vCPUs. Thus in turn allowing Linux VM usage atop Bhyve to enjoy 255+ vCPU VMs for those wanting to do so. Currently that is the only use of this Bhyve detection support in the Linux kernel.

[3]This patch has been queued into tip/tip.git's "x86/cpu" Git branch for detecting Bhyve. That patch should in turn land for the upcoming Linux 6.18 cycle. Linux 6.18 stable should be out in December, roughly around the same time of the expected stable release of FreeBSD 15.0.



[1] https://www.phoronix.com/search/Bhyve

[2] https://www.phoronix.com/search/FreeBSD+15.0

[3] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=215596ddc33f20945e8d1188a7e682831f0ef050