43fe83
From b46a1a6517874144f0cdf918f8148503bb5771e1 Mon Sep 17 00:00:00 2001
43fe83
Message-Id: <b46a1a6517874144f0cdf918f8148503bb5771e1.1382534061.git.jdenemar@redhat.com>
43fe83
From: Jiri Denemark <jdenemar@redhat.com>
43fe83
Date: Tue, 22 Oct 2013 16:09:06 +0100
43fe83
Subject: [PATCH] docs: Expand description of host-model CPU mode
43fe83
43fe83
https://bugzilla.redhat.com/show_bug.cgi?id=1014682
43fe83
43fe83
host-model is a nice idea but it's current implementation make it
43fe83
useless on some hosts so it should be used with care.
43fe83
43fe83
(cherry picked from commit 34adf622a352cbb80a98162a0f9ac3f9de3f95cb)
43fe83
43fe83
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
43fe83
---
43fe83
 docs/formatdomain.html.in | 11 ++++++++++-
43fe83
 1 file changed, 10 insertions(+), 1 deletion(-)
43fe83
43fe83
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
43fe83
index 512e0df..132c16c 100644
43fe83
--- a/docs/formatdomain.html.in
43fe83
+++ b/docs/formatdomain.html.in
43fe83
@@ -922,7 +922,16 @@
43fe83
           model even if the destination host contains more capable CPUs for
43fe83
           the running instance of the guest; but shutting down and restarting
43fe83
           the guest may present different hardware to the guest according to
43fe83
-          the capabilities of the new host.
43fe83
+          the capabilities of the new host. Beware, due to the
43fe83
+          way libvirt detects host CPU and due to the fact libvirt does not
43fe83
+          talk to QEMU/KVM when creating the CPU model, CPU configuration
43fe83
+          created using host-model may not work as expected. The
43fe83
+          guest CPU may differ from the configuration and it may also confuse
43fe83
+          guest OS by using a combination of CPU features and other parameters
43fe83
+          (such as CPUID level) that don't work. Until these issues are fixed,
43fe83
+          it's a good idea to avoid using host-model and use
43fe83
+          custom mode with just the CPU model from host
43fe83
+          capabilities XML.
43fe83
           
host-passthrough
43fe83
           
With this mode, the CPU visible to the guest should be exactly
43fe83
           the same as the host CPU even in the aspects that libvirt does not
43fe83
-- 
43fe83
1.8.4
43fe83