f9db6f3ab6
There are a some scenarios in which we want to prealloc guest memory (e.g. when requested in domain XML, when using hugepages, etc.). With 'regular' <memory/> models (like 'dimm', 'nvdimm' or 'virtio-pmem') or regular guest memory it is corresponding memory-backend-* object that ends up with .prealloc attribute set. And that's desired because neither of those devices can change its size on the fly. However, with virtio-mem model things are a bit different. While one can set .prealloc attribute on corresponding memory-backend-* object it doesn't make much sense, because virtio-mem can inflate/deflate on the fly, i.e. change how big of a portion of the memory-backend-* object is exposed to the guest. For instance, from a say 4GiB module only a half can be exposed to the guest. Therefore, it doesn't make much sense to preallocate whole 4GiB and keep them allocated. But we still want the part exposed to the guest preallocated (when conditions described at the beginning are met). Having said that, with new enough QEMU the virtio-mem-pci device gained new attribute ".prealloc" which instructs the device to talk to the memory backend object and allocate only the requested portion of memory. Now, that our algorithm for setting .prealloc was isolated in a single function, the function can be called when constructing cmd line for virtio-mem-pci device. Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>
Libvirt API for virtualization
Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the website:
License
The libvirt C API is distributed under the terms of GNU Lesser General Public License, version 2.1 (or later). Some parts of the code that are not part of the C library may have the more restrictive GNU General Public License, version 2.0 (or later). See the files COPYING.LESSER and COPYING for full license terms & conditions.
Installation
Instructions on building and installing libvirt can be found on the website:
https://libvirt.org/compiling.html
Contributing
The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
The libvirt project has two primary mailing lists:
- libvirt-users@redhat.com (for user discussions)
- libvir-list@redhat.com (for development only)
Further details on contacting the project are available on the website: