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When parsing the guest XML we must fill in the default guest arch if it is not already present because later parts of the parsing process need this information. If no arch is specified we lookup the first guest in the capabilities data matching the os type and virt type. In most cases this will result in picking the host architecture but there are some exceptions... - The test driver is hardcoded to always use i686 arch - The VMWare/ESX drivers will always place i686 guests ahead of x86_64 guests in capabilities, so effectively they always use i686 - The QEMU driver can potentially return any arch at all depending on what combination of QEMU binaries are installed. The domain XML hardware configurations are inherently architecture specific in many places. As a result whomever/whatever created the domain XML will have had a particular architecture in mind when specifying the config. In pretty much any sensible case this arch will have been the native host architecture. i686 on x86_64 is the only sensible divergance because both these archs are compatible from a domaain XML config POV. IOW, although the QEMU driver can pick an almost arbitrary arch as its default, in the real world no application or user is likely to be relying on this default arch being anything other than native. With all this in mind, it is reasonable to change the XML parser to allow the default architecture to be passed via the domain XML options struct. If no info is explicitly given then it is safe & sane to pick the host native architecture as the default for the guest. Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
libvirt library code README
===========================
The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.
The files directly in this directory are supporting the public API
entry points & data structures.
There are two core shared modules to be aware of:
* util/ - a collection of shared APIs that can be used by any
code. This directory is always in the include path
for all things built
* conf/ - APIs for parsing / manipulating all the official XML
files used by the public API. This directory is only
in the include path for driver implementation modules
* vmx/ - VMware VMX config handling (used by esx/ and vmware/)
Then there are the hypervisor implementations:
* bhyve - bhyve - The BSD Hypervisor
* esx/ - VMware ESX and GSX support using vSphere API over SOAP
* hyperv/ - Microsoft Hyper-V support using WinRM
* lxc/ - Linux Native Containers
* openvz/ - OpenVZ containers using cli tools
* phyp/ - IBM Power Hypervisor using CLI tools over SSH
* qemu/ - QEMU / KVM using qemu CLI/monitor
* remote/ - Generic libvirt native RPC client
* test/ - A "mock" driver for testing
* vbox/ - Virtual Box using native API
* vmware/ - VMware Workstation and Player using the vmrun tool
* xen/ - Xen using hypercalls, XenD SEXPR & XenStore
Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU and Xen drivers.
The ESX, Hyper-V, Power Hypervisor, Remote, Test & VirtualBox drivers all
implement the secondary drivers directly
* cpu/ - CPU feature management
* interface/ - Host network interface management
* network/ - Virtual NAT networking
* nwfilter/ - Network traffic filtering rules
* node_device/ - Host device enumeration
* secret/ - Secret management
* security/ - Mandatory access control drivers
* storage/ - Storage management drivers
Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories