Default guest instance misses some commonly expected features on Intel architectures

I prefer acpi capable by default like VMs created by virt-manager.

--- template.xml 2013-09-19 16:55:33 +0000
+++ template.xml 2013-11-20 23:20:18 +0000
@@ -3,6 +3,11 @@
     <type>hvm</type>
     <boot dev='hd'/>
   </os>
+ <features>
+ <acpi/>
+ <apic/>
+ <pae/>
+ </features>
   <devices>
     <interface type='network'>
       <source network='default'/>

Thank you for the bug report.

Ryan Harper has sent me a similar patch, but I was concerned that this breaks other guest architectures (eg. ARM) which may not necessarily have these features.

Ryan since sent me an updated patch which checks the host architecture. Sorry, Ryan, for not reviewing this sooner. I'm not sure this is the right approach either, since it's a guest architecture feature that we need to verify is suitable; the host should be irrelevant.

Comments appreciated.

AFAICT, there is no known way to confirm a guest architecture supports specific features. In libvirt today, all of the feature checks are done against the host architecture. Additionally, a quick check could validate, but I see no harm in adding <acpi> and other features into the template xml (or the host detection), guests that don't support ACPI or the other features will ignore them.

Sorry for the delay on this. Ryan has convinced me to go with the original patch and just change the template. This assumes that libvirt will ignore the features that it can't support on ARM in the future - or I'll need to address that then.

I will push this shortly.