From 34adf622a352cbb80a98162a0f9ac3f9de3f95cb Mon Sep 17 00:00:00 2001 From: Jiri Denemark Date: Thu, 17 Oct 2013 16:02:38 +0200 Subject: [PATCH] docs: Expand description of host-model CPU mode host-model is a nice idea but it's current implementation make it useless on some hosts so it should be used with care. --- docs/formatdomain.html.in | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index c5a3fa8059..491a6a9092 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -924,7 +924,16 @@ model even if the destination host contains more capable CPUs for the running instance of the guest; but shutting down and restarting the guest may present different hardware to the guest according to - the capabilities of the new host. + the capabilities of the new host. Beware, due to the + way libvirt detects host CPU and due to the fact libvirt does not + talk to QEMU/KVM when creating the CPU model, CPU configuration + created using host-model may not work as expected. The + guest CPU may differ from the configuration and it may also confuse + guest OS by using a combination of CPU features and other parameters + (such as CPUID level) that don't work. Until these issues are fixed, + it's a good idea to avoid using host-model and use + custom mode with just the CPU model from host + capabilities XML.
host-passthrough
With this mode, the CPU visible to the guest should be exactly the same as the host CPU even in the aspects that libvirt does not -- GitLab