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'passthrough' is Xen-Specific guest configuration option new to Xen 4.13
that enables IOMMU mappings for a guest and hence whether it supports PCI
passthrough. The default is disabled. See the xl.cfg(5) man page and
xen.git commit babde47a3fe for more details.
The default state of disabled prevents hotlugging PCI devices. However,
if the guest configuration contains a PCI passthrough device at time of
creation, libxl will automatically enable 'passthrough' and subsequent
hotplugging of PCI devices will also be possible. It is not possible to
unconditionally enable 'passthrough' since it would introduce a migration
incompatibility due to guest ABI change. Instead, introduce another Xen
hypervisor feature that can be used to enable guest PCI passthrough
<features>
<xen>
<passthrough state='on'/>
</xen>
</features>
To allow finer control over how IOMMU maps to guest P2M table, the
passthrough element also supports a 'mode' attribute with values
restricted to snyc_pt and share_pt, similar to xl.cfg(5) 'passthrough'
setting .
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Michal Privoznik <mprivozn@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
* 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, 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