Difference between revisions of "ERIKA3 on the Xen hypervisor"

Revision as of 18:58, 26 November 2018

Introduction

Xen is an open-source type-1 or bare-metal hypervisor that runs directly on the hardware and is responsible for handling CPU, memory, timers and interrupts.

The hypervisor is started by the boot loader and, once it is loaded, it starts the privileged domain Dom0 (short for "domain 0") containing the drivers of the system devices. Once Dom0 has started, one or more user domains, referred to as DomU, can be started and controlled in the Dom0. Xen supports both para-virtualized (PV) and fully hardware virtualized (HVM) user domains.

This tutorial will explain how to build and run ERIKA3 as Xen hardware-virtualized DomU on the x86-64 platform.

ERIKA3 Xen configuration

This section defines the configuration parameters that are used for running ERIKA3 as Xen DomU. Note that according to Xen configuration syntax, comment lines starts with the '#' symbol. The configuration file, referred to as erika3-xen.cfg, has to include the following basic parameters, such as domain name, memory requirements, virtualization mode and interfaces definition.

Name of domain (must be unique):

 # Name 
 name = "erika"

Initial memory allocation (MB) for ERIKA3 (should be at least 2M):

 # Memory and related 
 memory = 2048
 maxmem = 2048

Boot disk (where $ERIKA3_PATH is the path of the ERIKA3 bare-metal image):

 ## Boot
 disk 	= [ 'file:/home/evidence/erika3/erika3.iso,hdc:cdrom,r' ]
 boot 	= "c"

Virtualization mode:

 ## Virtualization type
 type = "hvm"

Enable Xen console:

 serial = "pty"

Network interfaces:

 ## Network
 vif	 = [ "mac=00:16:3e:51:fe:67,bridge=xenbr0,script=vif-bridge" ]

Domain exit behavior settings:

 ## Behaviour
 on_poweroff = "preserve"
 on_reboot = "destroy"
 on_crash = "destroy"

Build ERIKA3 for Xen

Building ERIKA3 for Xen requires building an ERIKA3 image for bare-metal as described here.

Run ERIKA3 as XEN HVM DomU

The Xen command to start the ERIKA3 DomU is the following:

 $ sudo xl create erika3-xen.cfg

where erika3-xen.cfg is the ERIKA3 configuration file. In order to connect to console directly when starting the ERIKA3 domU, launch the following command:

 $ sudo xl create -c erika3-xen.cfg

In case of console connection to the ERIKA3 DomU that is already running, the xen command is the following:

 $ sudo xl console erika

where 'erika' is the domain name defined in the configuration file.

In order to poweroff the ERIKA3 DomU, the Xen command is the following:

 $ sudo xl console erika

where 'erika' is the domain name defined in the configuration file.

ERIKA3 CPUs configuration

[TODO] In order to tune ERIKA3 DomU, Xen configuration could include CPUs affinity in order to pin ERIKA on a given CPU. Note that current implementation of ERIKA3 on x86-64 is single-core. Thus, the number of virtual CPUs is 1. Such virtual CPU can be pinned to a given physical CPU. Furthermore, Xen configuration can allow to create the ERIKA3 DomU and to assign a given Cpupool at creation. Cpupools allows to divide the physical cpus into distinct groups so that each pool can have its entirely separate scheduler (e.g., null-scheduler).

Number of virtual CPUs to use (default is 1):

 #Virtual CPUs
 vcpus	= 1

List of which CPUs this domain is allowed to use (in the example, it is the CPU with identifier 3):

 #CPUs, Hard affinity
 cpus = ['3']

Assign to a given CpuPool (in the example, the Cpupool has name 'NullPool'):

 #CpuPool
 pool="NullPool"

ERIKA3 Xen Passthrough

[TODO]

In order to give control of physical devices to ERIKA3 domU, Xen configuration should include the configuration for PCI passthrough. Note that the chosen PCI device has to be "assignable".

For example, the Xen configuration to allow the PCI passthrough for the Ethernet device with '00:1f.6' as BDF:

 ## ETH1 Passthrough
 pci_permissive=1
 pci = ['00:1f.6']