= Compute Clusters Integration for Debian Development and Building - Project Log =

== Environment Setup ==

[[http://open.eucalyptus.com|Eucalyptus]] uses [[http://libvirt.org|libvirt]] as a mechanism to interact with virtualization's hyphervisors such KVM, QEMU and others. This facility allow us to extend it's features and support arm architecture by using KVM-Qemu as emulator for libvirt's domain (Eucalyptus nc's).

In order to be able to use such facility there are few requirements that need to be met first:
 1. The first requirement is to have kvm-qemu running as hyphervisor, so that the arm architecture is supported as a libvirt capability. Otherwise kvm will not be able to make use of qemu-system-arm as libvirt capability. For this to happen you processor should support VT (virtualization technology) for AMD-based it's called svm and for Intel-based CPUs it's called vmx. You can check more information on [[KVM ]] and on VT support [[http://www.howtogeek.com/howto/linux/linux-tip-how-to-tell-if-your-processor-supports-vt/|here]].
 1. Second requirement is installing the required software eucalyptus software.


Virtualization facilities:
{{{
aptitude install kvm libvirt-bin qemu qemu-system
}}}

Eucalyptus packages and related software
{{{
aptitude install eucalyptus-cloud
}}}


== Eucalyptus code modification ==

=== Eucalyptus branch ===

I've branched LaunchPad Eucalyptus repo, then synced with the 2.3.0 -src-offline release. Currently the Launchpad branch is outdated from such release. You can use my branch by issuing the following command:

{{{
bzr branch http://stone-head.org/debian/eucalyptus-nc-arm
}}}

To build the software you need to use pkg-eucalyptus debian/ and issue:
{{{
svn-buildpackage -rfakeroot 
}}}

=== Related modifications ===


util/data.h
{{{typedef struct ncInstance_t }}}

defines the metadata for a nc. Main fields are the following:
{{{
    char instanceId[CHAR_BUFFER_SIZE];
    char imageId[CHAR_BUFFER_SIZE];
    char imageURL[CHAR_BUFFER_SIZE];
    char kernelId[CHAR_BUFFER_SIZE];
    char kernelURL[CHAR_BUFFER_SIZE];
    char ramdiskId[CHAR_BUFFER_SIZE];
    char ramdiskURL[CHAR_BUFFER_SIZE];
    char reservationId[CHAR_BUFFER_SIZE];
    char userId[CHAR_BUFFER_SIZE];
    int retries;

}}}

The plan is extend it to support an arch field.

util/data.c
{{{
allocate_instance( - params - ) 
}}} returns an instance.


node/handler_kvm.c
Creates the instance and calls libvirt.

node/handlers.c
Calls doInitialize() in node/handler_kvm.c that invokes the wrapper tool for XML domain file. It needs to make sure the arch field is being passed.

get_instance_xml invokes the wrapper tool and passes arguments to virsh.

tools/gen_kvm_libvirt_xml creates libvirt's XML Domain definition. Now it looks for an arch field to know that it needs to populate settings for ARM. However, it need the arch argument.

== ARM Image ==
 * ARM image based on current versatilepb kernel works fine and runs under qemu-system-arm. Not much trouble on building it. A nice resource is Aurel32's post. 

'''TODO''':
 * Update Aurel32's howto using latest versions.
 * Image cloudyfication, once the Eucalyptus support is in place. 

=== Proposal for Image Creation Automation ===
Adapt [[VMBuilder]] Debian's branch to support ARM [[CreateImage|image creation]] and install so that it can later be directly uploaded to an Eucalyptus Cloud, that supports ARM images.

'''Approach''':
 * Extend Debian's [[VMBuilder]] to support the versatilepb  (plugins/debian/distro.py)
 * Debian installation for the ARM image should be automatic ([[http://www.debian.org/releases/stable/armel/apb.html.en|preseeding]]). 
 * Install should use both kernel and initrd from Debian mirror to run the guest for installation. (qemu-system-arm ...)
 * For base system install it should use either an previously downloaded ISO (preferred) or directly a netinst. 
 * Installation should use preseeding to completely automate it and make it unattended.
 * Once installed, system configuration should be done by [[VMBuilder]]'s current procedure.
 * Image creation finishes and it's ready for euca-upload-image.

'''Challenges''':
 * [[VMBuilder]]: Clear rmadison dependency for kernel selection - https://bugs.launchpad.net/ubuntu/+source/vm-builder/+bug/560686
 * [[VMBuilder]]: OS installation automation. Run qemu-system-arm in "silent" mode using d-i ISO image + preseeding? *TBD*

'''Progress''':
 * [[VMBuilder]] currently supports disk creation using qcow2 format (GOOD).


Command for running my updated arm image.
{{{
echo "Install Debian..."
#qemu-system-arm -M versatilepb -kernel vmlinuz-2.6.32-5-versatile -initrd initrd.gz -hda disk.img -append "root=/dev/ram"


echo "Run Debian ARM..."
qemu-system-arm -M versatilepb -kernel vmlinuz-2.6.32-5-versatile -initrd initrd.img-2.6.32-5-versatile -hda disk.img -append "root=/dev/sda1"
}}}


== Eucalyptus integration ==
 * Eucalyptus uses libvirt as an API to interact with QEMU and KVM drivers (currently only supporting hypervisor mode) this enables to run compatible images, then creates nc (Euca nodes).
 * Supported arches are x86 and x86_64.
 * Supporting ARM should be feasible by hooking up with libvirt hypervisor capabilities that are already present and supported under latest Debian packages.
 * Once ARM is supported image generation / automatization could be the next step if time allows.

'''TODO''':
 * DONE: Figure out how to hook up arm support using Eucalyptus libvirt handler.
 * Relevant code for supporting arm on Eucalyptus is in:
  * C: 
   * node/handlers_kvm.{c,h} - handles nc creation.
   * util/data.{c,h} - handles instance creation
  * Perl: tools/gen_kvm_libvirt_xml - wrapper tool for creating KVM/QEMU libvirt's XML Domain definitiion. This needs to be heavily changed/updated - redesigned, to support non-x86 archs
 * There are some reported issues regarding PCI identification for qemu-system-arm, this need to be cleared later.


== TODO ==

 * Axis2 package in Debian. AXIS2_HOME should be set globally or include the jars in /usr/lib/java. Workaround: setting the env variable on .bashrc/.zshrc to avoid build errors from gatherlog/Makefile and others. 
 * Groovy build issues: General error during conversion: Invalid index.

== Resources ==
 * http://www.aurel32.net/info/debian_arm_qemu.php - Debian ARM using Qemu