A patch making it to a TIP Git branch this week adds Linux kernel support for detecting the FreeBSD Bhyve hypervisor, which will become important with today's growing server CPU counts.

As covered originally a few days ago, the Linux kernel has been working on Bhyve hypervisor detection for [1]being able to support more than 255 vCPUs . The FreeBSD 15.0 release coming out in December has 15-bit MSI enlightenment support for being able to handle more than 255 vCPUs. Thus for Linux VM usage with Bhyve there's now a need for this hypervisor detection.

[2]This patch made it into tip/tip.git's "x86/cpu" Git branch this week. With that milestone now achieved, the support should be merged in the coming weeks with the Linux 6.18 merge window.

"x86/cpu: Detect FreeBSD Bhyve hypervisor

Detect the Bhyve hypervisor and enable 15-bit MSI support if available.

Detecting Bhyve used to be a purely cosmetic issue of the kernel printing 'Hypervisor detected: Bhyve' at boot time.

But FreeBSD 15.0 will support¹ the 15-bit MSI enlightenment to support more than 255 vCPUs which means there's now actually some functional reason to do so."

Both [3]FreeBSD 15.0 and Linux 6.18 should coincidentally see their stable releases in December.



[1] https://www.phoronix.com/news/Linux-Bhyve-Detection

[2] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=x86/cpu&id=fa1d117162aa820a8f73a31ccab85bde6c84725b

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