From b46a1a6517874144f0cdf918f8148503bb5771e1 Mon Sep 17 00:00:00 2001
Message-Id: <b46a1a6517874144f0cdf918f8148503bb5771e1.1382534061.git.jdenemar@redhat.com>
From: Jiri Denemark <jdenemar@redhat.com>
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 <jdenemar@redhat.com>
---
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.</dd>
+ the capabilities of the new host. <strong>Beware</strong>, 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 <code>host-model</code> 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 <code>host-model</code> and use
+ <code>custom</code> mode with just the CPU model from host
+ capabilities XML.</dd>
<dt><code>host-passthrough</code></dt>
<dd>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