March 2017 - Users - libvirt List Archives

Re: [libvirt-users] CPU Pinning Help
by arrakis＠tsiom.com 21 Mar '17

21 Mar '17

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[libvirt-users] [RFC] per-device metadata
by Francesco Romani 21 Mar '17

21 Mar '17

Hi, Currently libvirt supports metadata in the domain XML. This is very convenient for data related to the VM, but it is a little awkward for devices. Let's pretend I want to have extradata (say, a specific port for a virtual switch) related to a device (say, a NIC). Nowadays I can store that data in the metadata section, but I need some kind of mapping to correlate this piece of information to the specific device. I can use the device alias, but this is not available when the device is created. This is also more complex when doing hotplug/hotunplug, because I need to do update device and update metadata; if either fails, the entire operation must be considered failed. It would be nice to be able to attach metadata to the device, and this is what I'm asking for/proposing in this mail. Would it be possible in a future libvirt release? If this is not possible, what's the best way to do the aforementioned mapping? If it's alias (or device address), how can I be sure than I'm addressing (no pun intended) the right device when I don't have them? (e.g. hotplug new device, or just first time VM created)? Thanks, -- Francesco Romani Red Hat Engineering Virtualization R & D IRC: fromani

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[libvirt-users] Get PID of a domain's QEMU instance from its domain ID
by Thibaut SAUTEREAU 21 Mar '17

21 Mar '17

Hello, I cannot find a way to retrieve PIDs of QEMU instances from libvirt domains' IDs (I'm using libvirt C API). I recognize it sounds like a bad idea doing so (and I know PIDs are explicitly made not available, as I gathered from the source code and on your IRC channel) but I need that to use the perf_event_open syscall in order to gather statistics on my QEMU/KVM guests. I also know libvirt now supports some perf events but only a few and I need more. I could submit patches to add them and I will definitely consider that but in the meantime... What would be the best way to get those PIDs? I tried using the XML file but PID is hidden in there too. I took a look at QEMU Machine Protocol. Now I'm going to walk /proc and match on guests names but it is not that elegant. Any ideas? Thanks, Thibaut S.

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[libvirt-users] CPU Pinning Help
by arrakis＠tsiom.com 20 Mar '17

20 Mar '17

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[libvirt-users] VIR_ERR_OPERATION_INVALID from virDomainDestroyFlags call
by Milan Zamazal 17 Mar '17

17 Mar '17

Hi, we experienced a strange, non-reproducible error after a successful migration to another host. When we called virDomainDestroyFlags with VIR_DOMAIN_DESTROY_GRACEFUL flag after the migration on the source host, we got VIR_ERR_OPERATION_INVALID (code 55) error. The same with repeated virDomainDestroyFlags calls. Normally, we would expect either success or VIR_ERR_NO_DOMAIN error. `virsh list' didn't show the VM. Can anybody please explain to us when this can happen and what the error means in this context? When we have good reasons to believe that the VM is down (e.g. after a migration call successfully finishes) and we receive such an error from virDomainDestroyFlags, is it safe to assume the VM is basically gone and can we perform standard cleanup actions (like removing related files from the host file system)? Thank you, Milan

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[libvirt-users] migrating from XenServer / XCP to libvirt/KVM
by Daniel Pocock 15 Mar '17

15 Mar '17

I've been using XenServer / XCP (with the "xe" toolset) for a number of years for hosting servers used for development and free software projects and I'm now looking at migrating all those environments to libvirt / KVM. I had a look at the wiki[1] already and didn't see XenServer mentioned there. Could anybody help comment on or explain a few things: - comparison between XenServer and libvirt: I notice many similar concepts, for example, XenServer has storage repositories and libvirt has storage pools. However, in many examples such as this[2] it appears that libvirt requires more manual effort. For example, when you create a storage repository in XenServer, the tool takes a physical block device as input and creates the necessary volume group, logical volume and a filesystem. In that libvirt example, it appears each of those steps must be done manually. The networking examples are similar: the XenServer tools do all the Open vSwitch stuff behind the scenes but in the libvirt examples it appears necessary to create the bridge manually before telling libvirt about it. Is this all correct or are the examples I've seen out of date? Do more recent (or future) releases of libvirt aim to automate/hide more of these things? - what is best practice for virtual disk images? Does libvirt always use files (like XenServer) or can/should block devices be used directly? If using files, is any special care needed to avoid block alignment problems? - are there any guides or tools recommended for migrating small XenServer environments (less than 50 domains on a single physical node) to libvirt + KVM? - is there a list of small things that need to change in a VM before running it under libvirt / KVM? I'm guessing this might include bootloader config, updating the kernel, changing block device names in /etc/fstab and changing network device names in scripts - are there any others? - can anybody comment on more tricky issues that may arise in such a migration, for example, will a Windows VM be likely to run without modification when migrated from XenServer to libvirt/KVM or will it need extra drivers added or anything else before the migration? Regards, Daniel 1. http://wiki.libvirt.org/page/Main_Page 2. https://keepingitclassless.net/2014/01/libvirt-intro-basic-configuration/

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[libvirt-users] MIPS emulation broken - No PCI buses available
by Ian Pilcher 15 Mar '17

15 Mar '17

I am trying to create a QEMU MIPS guest, so that I can test some code for big-endian safety. Every attempt to create a MIPS guest is giving me an error: Unable to complete install: 'XML error: No PCI buses available' It seems like this is a known issue. https://www.redhat.com/archives/libvir-list/2016-May/msg00197.html However, I am still getting this on a fully updated Fedora 25 system with libvirt-2.2.0-2.fc25.x86_64. -- ======================================================================== Ian Pilcher arequipeno(a)gmail.com -------- "I grew up before Mark Zuckerberg invented friendship" -------- ========================================================================

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[libvirt-users] trouble after upgrading from 3.0.0 to 3.1.0
by Michael Ströder 15 Mar '17

15 Mar '17

HI! After the last OS update (openSUSE Tumbleweed) with libvirt being updated from 3.0.0 to 3.1.0 starting the VMs (qemu-kvm) does not work anymore: error: internal error: child reported: Kernel does not provide mount namespace: Permission denied Kernel was updated before to 4.10.1 and worked just fine with libvirt 3.0.0 packages. Any clue how to work around that? Ciao, Michael.

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Re: [libvirt-users] [libvirt] libvirt and dmesg
by Cedric Bosdonnat 15 Mar '17

15 Mar '17

Hello Pierre-Jacques, First note that you posted your message on the developer's mailing list. For such user questions, rather email: https://www.redhat.com/mailman/listinfo/libvirt-users According to https://linuxcontainers.org/lxc/manpages//man5/lxc.container.conf.5.html lxc.kmsg is only used to symlink /dev/kmsg to /dev/console. Thus setting this to 0 only results in the lack of that symlink. libvirt doesn't setup this link at all, may be it is coming from the lxc domain root file system. On Wed, 2017-03-15 at 08:49 +0100, Michel Pierre-Jacques wrote: > Hi all, il try to find the way to obtain the same use as in the > lxc config file lxc.kmsg=0 > > how to do that, with the xml of a lxc domain, i make lot of try without > success . > > is there another way to deny access to the dmesg for a libvirt lxc > domain ? >From what I see, dmesg doesn't necessarily requires /dev/kmsg (at least on opensuse). So blocking it may be more tricky. May be you should tell us more how you setup your container. -- Cedric

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[libvirt-users] question about libvirt and suspending guests during live migration
by Chris Friesen 13 Mar '17

13 Mar '17

Hi, I hope someone can help me out. I'm running into an issue with libvirt 1.2.12 reporting "operation failed: domain is no longer running" for a migration when qemu thinks it was fine. The steps are: 1) create guest with stress test running in it to dirty memory at a high rate (fast enough that it would not normally complete live-migration) 2) trigger live migration with dom.migrateToURI2() 3) while migration is in progress, call dom.suspend() on the migrating domain. What I see at this point is the following: a) At time 50.465 the monitoring code sees a VIR_DOMAIN_EVENT_SUSPENDED event, as expected. b) An instrumented qemu logs the following: 51.143: done transferring state 51.143: done migration 51.144: qmp_query_migrate reporting state completed c) At time 51.468 the monitoring code sees a VIR_DOMAIN_EVENT_RESUMED event, with detail of VIR_DOMAIN_EVENT_RESUMED_UNPAUSED c) At time 51.469 the the monitoring code sees a VIR_DOMAIN_EVENT_RESUMED event, with detail of VIR_DOMAIN_EVENT_RESUMED_MIGRATED e) At time 51.471 the dom.migrateToURI2() call raises an exception (this is python). The corresponding libvirt log file shows: "error : virNetClientProgramDispatchError:177 : operation failed: domain is no longer running" For what it's worth, the problem seems to be fixed in libvirt 1.2.17. In that version and later I don't see the VIR_DOMAIN_EVENT_RESUMED event, the migration just completes. I'm looking at the libvirt history, but I figured I'd ask here too... Thanks, Chris

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