From b46a1a6517874144f0cdf918f8148503bb5771e1 Mon Sep 17 00:00:00 2001 Message-Id: From: Jiri Denemark Date: Tue, 22 Oct 2013 16:09:06 +0100 Subject: [PATCH] docs: Expand description of host-model CPU mode https://bugzilla.redhat.com/show_bug.cgi?id=1014682 host-model is a nice idea but it's current implementation make it useless on some hosts so it should be used with care. (cherry picked from commit 34adf622a352cbb80a98162a0f9ac3f9de3f95cb) Signed-off-by: Jiri Denemark --- 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 512e0df..132c16c 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -922,7 +922,16 @@ 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 -- 1.8.4