Hi, Here’s a quick status update:
On 16 May 2014, at 15:22, Dave Scott <dave.sc...@citrix.com> wrote: > Hi, > > On 14 May 2014, at 09:53, sebgoa <run...@gmail.com> wrote: > >> >> On Apr 9, 2014, at 2:37 PM, Dave Scott <dave.sc...@citrix.com> wrote: >> >>> Hi, >>> >>> Following up from Tim's "Support pure Xen as a hypervisor" proposal last >>> month[1] I'd like to start working on this and maybe even make a little bit >>> of progress while I'm at CCC in Denver. >>> >>> Helpfully James Bulpin managed to get CS + libvirt + xen to start an >>> instance in a simple configuration. Although the patches[2] are not >>> intended to be production-ready :) they help highlight some of the areas we >>> need to change. >> >> Dave, just to let you know that Tim has done some important "refactoring" to >> split up XenServer hypervisor in CS between Xen and XenServer. That way we >> could keep using xapi for XS but start moving to libvirt for Xen. >> >> Tim worked in the xen2server branch (don't ask about the name, I messed it >> up…:) ). >> >> https://git-wip-us.apache.org/repos/asf?p=cloudstack.git;a=shortlog;h=refs/heads/xen2server >> >> Would be nice to see some of the libvirt stuff in that branch to handle a >> new driver for Xen. >> >> Since the two hypervisors will be split up, we could still drop in some >> early libvirt patches to handle Xen and put this in 4.5 as a wip. > > Thanks for the links. > > I’m slowly building up a set of patches here: > > https://github.com/djs55/cloudstack/tree/virsh-capabilities > > I think once I’ve gotten to a stable-ish point I’ll rebase on top of Tim’s > branch. > > So far I’ve > * changed the hypervisor detection to use ‘virsh capabilities’ in one place > and ‘cat /sys/hypervisor/type’ in another. Thinking about it again, I think > it’s probably best to standardise on /sys/hypervisor/type since that will > succeed irrespective of whether the libvirtd service is chkconfig’d on or not. > > * in the python cloudutils system setup stuff isKvmEnabled() has become > isHypervisorEnabled() > > * added a XenLibvirtDiscoverer similar to the LXC one > > * fixed what I believe is a race in sshExecuteCmdOneShotWithExitCode (which > seems to hit me every time, I don’t know why other people seem to be immune > from it): see CLOUDSTACK-6621 and review board request 21261 > > * added the new hypervisor to hypervisor.list and > system.vm.default.hypervisor, so it appears in the UI properly > > * registered a system VM template in the database, using the same qcow2 image > as KVM > > For my test host I’m using a XenServer nightly snapshot which comes with a > nice modern xen and kernel, and is easy to install bleeding-edge libvirt on > top. I had to tweak the kernel configuration and the network configuration > but I’m hoping to make it work out of the box in future. > > When I deploy my ‘datacenter’ the discovery phase works, the agent connects > and looks healthy in the logs and the UI. The next step is to figure out why > the system VM template isn’t being copied to primary storage — for some > reason the copy isn’t being attempted but I can’t see any obvious reason why. I’m now at the stage of getting my system VMs to start via libvirt. The main missing feature is support for <channels>: low-bandwidth private host<->guest control channels. These channels are generally useful things and are needed by other projects (like oVirt), so I’d like to add them to libxl and libvirt’s libxl driver. There’s a thread on xen-devel and libvir-devel if anyone’s interested: http://www.redhat.com/archives/libvir-list/2014-June/msg00180.html Once the <channels> are sorted, basic VM operations should work. The next step would be to rebase my patches on top of Tim’s renaming changes and tidy them up for review. Cheers, Dave > > Cheers, > Dave > >> >> -Sebastien >> >>> >>> Some of the areas are: >>> >>> 1. hypervisor detection >>> >>> Where we currently look for KVM specifically ("lsmod | grep kvm") we could >>> switch to either detecting any Linux hypervisor (by reading >>> /sys/hypervisor/type) and assuming if a hypervisor is present then we can >>> use libvirt on it (is this a fair assumption?) Or we could white-list “kvm” >>> or “xen”. Or we could query libvirt directly (perhaps via 'virsh >>> capabilities'?) >>> >>> 2. fiddling with the domain.xml >>> >>> When starting a domain via libvirt the XML configuration has >>> hypervisor-specific stuff in it. Some of this is easy to change like: >>> >>> <domain type='kvm'> >>> >>> obviously becomes >>> >>> <domain type='xen'> >>> >>> and >>> >>> <emulator>/usr/libexec/qemu-kvm</emulator> >>> >>> should probably be >>> >>> <emulator>/some/other/path/qemu-dm</emulator> >>> >>> Some is a bit more invasive (to the VM) such as the virtual hardware type >>> should be switched from "virtio" to "xen" (and the block device in Linux >>> will change from /dev/vd* to /dev/xvd*) and we'll have to either implement >>> or work around the lack of >>> >>> <channel type='unix'> ... >>> >>> -- I presume this is a control channel into the system VM. Perhaps we could >>> implement this in libvirt/libxl using vchan? >>> >>> 3. system VMs? >>> >>> It would be very convenient if the system VM images could work on both xen >>> and KVM. This is probably doable as long as we don't bake in virtual >>> hardware specific information (such as /dev/vda) in the image. We could use >>> the qcow2 format in both cases. What do you think? >>> >>> … and I’m sure there’s more. >>> >>> Anyway, feedback would be welcome. If anyone else in Denver wants to chat, >>> then come grab me later! >>> >>> Cheers, >>> Dave Scott >>> >>> [1] >>> http://mail-archives.apache.org/mod_mbox/cloudstack-users/201403.mbox/%3ccajgxtbnbmqtq81ralgh2kma7v5wjyzkr3xnyasmkc_br+uk...@mail.gmail.com%3e >>> >>> [2] https://github.com/jamesbulpin/cloudstack/commits/jamesb_xen_exploratory
