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[Libvir] Request and proposition about hardware capabilities in virNodeInfo


To administrate virtual machines by using livbvirt, we need to known if the underlying hardware platform supports hvm (Intel-VT or AMD-V) or not. Currently, this information is returned by the "xm info" command of Xen in the "xen_caps" line but there is no equivalent in libvirt. So we propose to add this information in libvirt API.

There is three possibilities for doing that:
1) Add one or several fields in the virNodeInfo structure returned by the virNodeGetInfo() function. These fields would be either strings such as strings returned by "xm info" or either bit fields with one bit per hardware capability. 2) Add one or several specific functions returning a boolean value for each hardware capability we want to test. 3) Add a specific function which returns either a bit fields of all the hardware capabilities or a structure such as virNodeInfo but far more complete.

The problem with the proposition #1 is that the size of the virNodeInfo structure is changed. This implies for all libvirt users to recompile their programs linked with libvirt to avoid a 'core dump' at the execution. This is the reason why propositions 2 and 3 exist.

NB: On an IA32 system, we can check flags in /proc/cpuinfo but on an IA64 platform with Montecito processors, there is no information about hardware capabilities in /proc/cpuinfo and the only way to known if the hardware supports hvm is by using the 'xm info' command.

What is your opinion about these propositions ?


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