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Merge pull request #571 from egernst/update-on-vmms

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architecture: update architecture docs to reflect VMM support
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Xu Wang 2019-11-13 15:03:18 +08:00 committed by GitHub
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@ -103,17 +103,16 @@ container processes.
## Hypervisor
Kata Containers is designed to support multiple hypervisors. For the 1.0 release,
Kata Containers uses just [QEMU](http://www.qemu-project.org/)/[KVM](http://www.linux-kvm.org/page/Main_Page)
to create virtual machines where containers will run:
Kata Containers is designed to support multiple virtual machine monitors (VMMs) and hypervisors.
![QEMU/KVM](arch-images/qemu.png)
As of the 1.9 release, Kata Containers supports [QEMU](http://www.qemu-project.org/)/[KVM](http://www.linux-kvm.org/page/Main_Page),
[Firecracker](https://github.com/firecracker-microvm/firecracker)/KVM, as well as the [ACRN hypervisor](https://projectacrn.org/).
### QEMU/KVM
Depending on the host architecture, Kata Containers supports various machine types,
for example `pc` and `q35` on x86 systems, `virt` on ARM systems and `pseries` on IBM Power systems. The default Kata Containers
machine type is `pc`. The default machine type and its [`Machine accelerators`](#machine-accelerators) can
machine type is `pc`. The machine type and its [`Machine accelerators`](#machine-accelerators) can
be changed by editing the runtime [`configuration`](#configuration) file.
The following QEMU features are used in Kata Containers to manage resource constraints, improve
@ -134,19 +133,6 @@ are used in Kata Containers:
`q35` machine types. `nvdimm` is used to provide the root filesystem as a persistent
memory device to the Virtual Machine.
Although Kata Containers can run with any recent QEMU release, Kata Containers
boot time, memory footprint and 9p IO are significantly optimized by using a specific
QEMU version called [`qemu-lite`](https://github.com/kata-containers/qemu/tree/qemu-lite-2.11.0) and
custom machine accelerators that are not available in the upstream version of QEMU.
These custom machine accelerators are described below.
- `nofw`: this machine accelerator is x86 specific and only supported by `pc` and `q35`
machine types. `nofw` is used to boot an ELF format kernel by skipping the BIOS/firmware
in the guest. This custom machine accelerator improves boot time significantly.
- `static-prt`: this machine accelerator is x86 specific and only supported by `pc`
and `q35` machine types. `static-prt` is used to reduce the interpretation burden
for guest ACPI component.
#### Hot plug devices
The Kata Containers VM starts with a minimum amount of resources, allowing for faster boot time and a reduction in memory footprint. As the container launch progresses, devices are hotplugged to the VM. For example, when a CPU constraint is specified which includes additional CPUs, they can be hot added. Kata Containers has support for hot-adding the following devices:
@ -155,6 +141,13 @@ The Kata Containers VM starts with a minimum amount of resources, allowing for f
- VFIO
- CPU
### Firecracker/KVM
As of the 1.5 release of Kata Containers, Firecracker VMM is supported. Because of its limited
device support, Firecracker does not support filesystem sharing (good for security and footprint!) As a result,
only block-based storage drivers are supported. Similarly, Firecracker does not support updating
container resources after boot (there is not any device hotplug support), nor does it support VFIO.
### Assets
The hypervisor will launch a virtual machine which includes a minimal guest kernel