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Which hypervisor provides more reliable support for the most popular two BSDs?

I read an article that Linode moved to KVM from XEN, and found a page named 'guest support status' on linux-kvm.org, but I can't find much recent info on BSD support in XEN.

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  • I've had great luck with some flavors of FreeBSD, particularly PC-BSD, on qemu-kvm. No experience with xen or OpenBSD.
    – airhuff
    Jan 20 '17 at 4:19
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OpenBSD works better on KVM. OpenBSD only supports Xen HVM, not PVM.

I can't help you with FreeBSD.

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Xen:

  • Since 5.9 OpenBSD included PVHVM drivers enabled by default. This commit done by mikeb confirms. This was written from scratch, and there is even a comparison with the FreeBSD code and how OpenBSD drivers are simpler and yet powerfull. The xen driver probes for paravirtualized devices such as disk and network interfaces and performs HVM domU guest initialization, abstraction for virtual Xen interrupts and access to the XenStore configuration storage.
  • FreeBSD works the same way with PVHVM drivers. It's not full PV, but it benefits from drivers with PV features. The difference here is that with some tweaking, you can run FreeBSD as Dom0

Related links:

KVM:

  • Since 5.3, OpenBSD supports virtio with the 0.95 spec with the following drivers being commited some releases later: vio(4) - network device, vioblk(4) - disk, viomb(4) - memory ballooning driver, viornd(4) - random number device, vioscsi(4) - SCSI adapter; Note that other virtualization technologies support virtio(VirtualBox, Xen, bhyve). This interface was ported from NetBSD drivers.
  • The same way, FreeBSD implements virtio driver however, you need to compile them if you are running a version older than 10.0(the manpage seems to be outdated, as for today modules are included on GENERIC). You should have good performance the same way as OpenBSD running on KVM, since both OS's have the PVH drivers for i/o, block, ethernet, scsi and balooning.

tl,dr: Both virtualization solutions will give you HVM with PVH drivers for those guests. Performance should be the same or near.

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