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⇱ Linux Adding Detection For BSD's Bhyve Hypervisor To Support 255+ vCPUs - Phoronix


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Linux Adding Detection For BSD's Bhyve Hypervisor To Support 255+ vCPUs

Written by Michael Larabel in BSD on 19 August 2025 at 07:52 AM EDT. 18 Comments
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 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.

👁 Bhyve logo


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.

Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.