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[Libvirt][emulator-cores][dpdk] Emulatorpin cpuset best practices
by Laurent Dumont 07 Jun '22

07 Jun '22

Hey folks, I am curious to understand a bit more the core use of the emulatorpin CPUs with libvirt. For example : <vcpupin vcpu='0' cpuset='34'/> <vcpupin vcpu='1' cpuset='14'/> <vcpupin vcpu='2' cpuset='10'/> <vcpupin vcpu='3' cpuset='30'/> <emulatorpin cpuset='10,14,30,34'/> In this case : - The VM has 4 vCPUs. - Each of the core is pinned to a physical/thread core - 34,14,10,30 - The emulatorpin is also attached to the same physical CPUs. In our case : - Same setup for cores. - Running DPDK inside the virtual machine. - The compute/libvirt is using OVS but without DPDK. What we saw is the following : - DPDK is polling two cores at 100% to process packets. - From the compute metrics, we see USER %usage at 100% when the application starts. - From the compute metrics, as traffic increases, we see %SYSTEM going up. - As %SYSTEM goes up, %USER goes down. We are not quite sure, but we are wondering if this could cause a direct impact to the ability of DPDK to process traffic at the same X speed? - We can "live" move the emulator CPU to other cores. - This seems to be the recommended default setup for VNF/NFV deployments. Feels like I am missing a piece of the puzzle but gotta start somewhere! Thanks!

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how to use "virsh shutdown domain --mode [initctl|signal|paravirt) ?
by Lentes, Bernd 01 Jun '22

01 Jun '22

Hi, ocasionally my Virtual Domains running on a pacmekaer cluster don't shutdown, although beeing told to do it. "virsh help shutdown" says: ... --mode <string> shutdown mode: acpi|agent|initctl|signal|paravirt How is it possible to use initctl or signal or paravirt ? What do i have to do ? What are the prerequisites ? Bernd -- Bernd Lentes System Administrator Institute for Metabolism and Cell Death (MCD) Building 25 - office 122 HelmholtzZentrum München bernd.lentes(a)helmholtz-muenchen.de phone: +49 89 3187 1241 fax: +49 89 3187 2294 http://www.helmholtz-muenchen.de/mcd Public key: 30 82 01 0a 02 82 01 01 00 b3 72 3e ce 2c 0a 6f 58 49 2c 92 23 c7 b9 c1 ff 6c 3a 53 be f7 9e e9 24 b7 49 fa 3c e8 de 28 85 2c d3 ed f7 70 03 3f 4d 82 fc cc 96 4f 18 27 1f df 25 b3 13 00 db 4b 1d ec 7f 1b cf f9 cd e8 5b 1f 11 b3 a7 48 f8 c8 37 ed 41 ff 18 9f d7 83 51 a9 bd 86 c2 32 b3 d6 2d 77 ff 32 83 92 67 9e ae ae 9c 99 ce 42 27 6f bf d8 c2 a1 54 fd 2b 6b 12 65 0e 8a 79 56 be 53 89 70 51 02 6a eb 76 b8 92 25 2d 88 aa 57 08 42 ef 57 fb fe 00 71 8e 90 ef b2 e3 22 f3 34 4f 7b f1 c4 b1 7c 2f 1d 6f bd c8 a6 a1 1f 25 f3 e4 4b 6a 23 d3 d2 fa 27 ae 97 80 a3 f0 5a c4 50 4a 45 e3 45 4d 82 9f 8b 87 90 d0 f9 92 2d a7 d2 67 53 e6 ae 1e 72 3e e9 e0 c9 d3 1c 23 e0 75 78 4a 45 60 94 f8 e3 03 0b 09 85 08 d0 6c f3 ff ce fa 50 25 d9 da 81 7b 2a dc 9e 28 8b 83 04 b4 0a 9f 37 b8 ac 58 f1 38 43 0e 72 af 02 03 01 00 01

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Virtiofs xattr options on domain xml
by ksobrenat32 23 May '22

23 May '22

Hi! I have a debian 11 (bullseye) machine running libvirtd version 7.0.0 and a RHEL 9 virtual machine that I need to share a disk and though about virtiofs. The disk is a btrfs disk and I have successfully mount it with: <filesystem type='mount' accessmode='passthrough'> <driver type='virtiofs' queue='1024'/> <binary path='/usr/lib/qemu/virtiofsd' xattr='on'> <cache mode='always'/> <lock posix='on' flock='on'/> </binary> <source dir='/mnt/WD-Disk'/> <target dir='media'/> <alias name='fs0'/> <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/> </filesystem> The problem I have is with selinux, when I try to change the context of a file inside the virtual machine I get a 'Operation not permitted' error, I can change the context in the Debian host and see the changes in the virtual machine but I would want to be able to change the context from the vm to able to use podman containers with selinux enabled. I see on the docs https://qemu.readthedocs.io/en/latest/tools/virtiofsd.html#selinux-support you can run virtiofsd with a xattr option so it is compatible with selinux but I do not find a way to change the domain xml to add this option, is there a way to add this option? Does a better option exists (maybe on the guest side)?

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something (qemu?) is leaking
by lejeczek 23 May '22

23 May '22

Hi guys. I do a simple thing which should be easy to reproduce. -> $ virt-install -n rum1 --virt-type kvm --os-variant centos8 --memory $((4*1024)) --disk=/VMs3/rum1.qcow2,device=disk,bus=virtio --network network=10_3_1,model=virtio --graphics=listen=0.0.0.0 --cpu EPYC-Rome --vcpus 3 --cdrom /VMs3/CentOS-Stream-9-latest-x86_64-dvd1.iso During manual setup in the VM I set 'hostname' to something and when installation begins and disk config stage takes place I can see - and later when VM(c9s) is ready can confirm - that VG name is taken from another VM defined/running on the host. Host is c9s with: qemu-kvm-7.0.0-1.el9.x86_64 libvirt-daemon-8.2.0-1.el9.x86_64 5.14.0-86.el9.x86_64 Does anybody see this/similar? many thanks, L.

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Slow VM start/revert, when trying to start/revert dozens of VMs in parallel
by Petr Beneš 20 May '22

20 May '22

Hi, my problem can be described simply: libvirt can't handle starting dozens of VMs at the same time. (technically, it can, but it's really slow.) We have an AMD machine with 256 logical cores and 1.5T ram. On that machine there is roughly 200 VMs. Each VM is the same: 8GB of RAM, 4 VCPUs. Half of them is Win7 x86, the other half is Win7 x64. VMs are using qcow2 as the disk image. These images reside in the ramdisk (tmpfs). We use these machines for automatic malware analysis, so our scenario consists of this cycle: - reverting VM to a running state - execute sample inside of the VM for ~1-2 minutes - shutdown the VM Of course, this results in multiple VMs trying to start at the same time. At first, reverts/starts are really fast - second or two. After about a minute, the "revertToSnapshot" suddenly takes 10-15 seconds, which is really unacceptable. For comparison, we're running the same scenarion on Proxmox, where the revertToSnapshot usually takes 2 seconds. Few notes: - Because of this fast cycle (~2-3 minutes) and because of VMs taking 10-15 seconds to start, there is barely more than 25-30 VMs running at once. We would really love to utilise the whole potential of such beast machine of ours, and have at least ~100 VMs running at any given time. - During the time running, the avg. CPU load isn't higher than 25%. Also, there's only about 280 GB of RAM used. Therefore, it's not limitation of our resources. - When the framwork is running and libvirt is making its best to start our VMs, I noticed that every libvirt operation is suddenly very slow. Even simple "virsh list [--all]" takes few seconds to complete, even though it finishes instantly when no VM is running/starting. I was trying to search for this issue, but didn't really find anything besides this presentation: https://events19.linuxfoundation.org/wp-content/uploads/2017/12/Scalability… However, I couldn't find those commits in your upstream. Is this a known issue? Or is there some setting I don't know of which would magically make the VMs start faster? As for steps to reproduce - I don't think there is anything special needed. Just try to start/destroy several VMs in a loop. There is even provided one-liner for that in the presentation above. ``` # For multiple domains: # while virsh start $vm && virsh destroy $vm; do : ; done # → ~30s hang ups of the libvirtd main loop ``` Best Regards, Petr

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macvtap with disconnected physical interface
by Gionatan Danti 19 May '22

19 May '22

Dear list, I just discovered the hard way that if the lower lever physical interface of a macvlan bridge is disconnected (ie: by unplugging the eth cable, resulting in no carrier), inter-guest network traffic from all virtual machines bound to the disconnected interface is dropped. This behavior surprises me, as with the classic bridges I can disconnect the underlying physical interface without causing any harm to inter-guest traffic. Am I doing something wrong, or this really is the expected behavior? If so, can I force the macvtap interfaces to bridge traffic even when the underlying physical interface is disconnected? Regards. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti(a)assyoma.it - info(a)assyoma.it GPG public key ID: FF5F32A8

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Updating domains definitions via API
by Darragh Bailey 17 May '22

17 May '22

Hi, Looking into a bug in vagrant-libvirt where an error during the update will cause the domain to be completely discarded. https://github.com/vagrant-libvirt/vagrant-libvirt/issues/949 Basically I think it stems from doing an undefine -> create with XML new process, which if there is an issue with the new XML due to KVM module not loaded or something similar it will be rejected, but unfortunately it is also unlikely to allow the old definition to be restored either. I'm looking around to try and see if there is an API (specfically in ruby-libvirt) for updating the domain definition, so that if the new XML is rejected at least the old definition remains, and so far I'm drawing a blank. Is the only option here to write using a temporary domain name, then remove the old domain and rename the new definition to the old domain? Or have I missed the obvious API analogous to the edit functionality? -- Darragh Bailey "Nothing is foolproof to a sufficiently talented fool" - unknown

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Problem calling 'virsh' in a script
by Digimer 16 May '22

16 May '22

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Any size limitation on the backing store?
by Jeff Brown 10 May '22

10 May '22

We have a few QCOW2 images that have grown rather large (> 250GB) and to back them up across the VLAN is resource intensive and time consuming. What I'd like to do to optimise backups is freeze the backing store and always run the VMs in 'snapshot 1', and then run 'snapshot 2' to backup 'snapshot 1' to reciprocal failover hypervisors in the DC. I do know it's common practice to even run multiple VMs off a single "golden image" backing store, but I'm concerned about the performance impact with such a large backing store, and 'snapshot 1' growing at ~10GB a year. With that in mind, it should be feasible to pivot 'snapshot 1' into the backing image periodically. Further, I am aware of incremental backups which Debian 11 doesn't yet support. I think it's coming in Debian 12, but some of our servers are actually still on Debian 10. jeff@abacus:/var/lib/libvirt/images$ virsh backup-begin dev error: Operation not supported: incremental backup is not supported yet In a nutshell, is it feasible to run off an > 250GB and growing backing store? Thanks in advance for any advice. -- Jeff Brown Future Foundation Cell 074 101 5170 VoIP 087 550 1210 Fax: 086 532 3508

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virtqemud high CPU load
by lejeczek 06 May '22

06 May '22

Hi guys, Anybody on centos9? With latest updates I get 100% load (so one core fully loaded) almost all the time, I don't remember that being the case before. 'virtqemud' itself does not log much, with default verbosity. Any thoughts? many thanks, L.

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Issue with Guest and 2 Displays
by Thomas Luening 29 Apr '22

29 Apr '22

Hi @ all Since switching from Debian 10 to Debian 11, I've had a new small unsolved problem... with essentially the same customizing as before. It all takes place on my local Desktop-PC, where I have set up a restricted VM for actions in the internet. After I started the VM locally on my PC, I can operate the VM with the virtviewer without any errors. If I then open the second monitor via the Menu 'View->Display', a blank white window appears with the message "Waiting for display 2". xrandr correctly shows the second display as disconnected and also all available display-modes. After the following command xrandr --output Virtual-2 --auto --right-of Virtual-1 both (!) displays are white and both are waiting for a display.... and nothing works anymore. A previously started SSH connection to the VM from the PC shows the following for this moment: tom@pc:~ $ ssh 192.168.100.10 $ tom@vm:~ $su- Password: root@vm:~ # journalctl -f Apr 29 16:24:34 internet kernel: [drm] driver is in bug mode Apr 29 16:24:44 internet spice-vdagent[809]: Unable to find a display id for output index 2) Apr 29 16:24:44 internet spice-vdagent[809]: Unable to find a display id for output index 3) Apr 29 16:24:44 internet spice-vdagent[809]: Unable to find a display id for output index 2) Apr 29 16:24:44 internet spice-vdagent[809]: Unable to find a display id for output index 3) Apr 29 16:24:44 internet kernel: input: spice vdagent tablet as /devices/virtual/input/input7 It is no longer possible to restart the VM via "systemctl reboot", the VM is probably stuck in some systemd-timeouts, only "systemctl reboot -ff" leads to a reboot as a hard intervention. Does anyone know this problem? Is there a solution for this, to get the second display working? Below some relevant system-informations of my PC and the VM. root@pc:~ $ lsb_release -a Distributor ID: Debian Description: Debian GNU/Linux 11 (bullseye) Release: 11 Codename: bullseye root@pc:~ # uname -a Linux pc 5.10.0-13-amd64 #1 SMP Debian 5.10.106-1 (2022-03-17) x86_64 GNU/Linux root@pc:~ # cat /etc/libvirt/qemu/internet.xml | grep '<video' -A 3 <video> <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='2' primary='yes'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </video> tom@vm:~ $ lsb_release -a Distributor ID: Debian Description: Debian GNU/Linux 11 (bullseye) Release: 11 Codename: bullseye tom@vm:~ $ dpkg -l | grep -i spice ii spice-vdagent 0.20.0-2 amd64 Spice agent for Linux tom@vm:~ $ systemctl status spice-vdagent.service ● spice-vdagentd.service - Agent daemon for Spice guests Loaded: loaded (/lib/systemd/system/spice-vdagentd.service; indirect; vendor preset: enabled) Active: active (running) since Fri 2022-04-29 16:00:56 CEST; 16min ago TriggeredBy: ● spice-vdagentd.socket Process: 847 ExecStart=/usr/sbin/spice-vdagentd $SPICE_VDAGENTD_EXTRA_ARGS (code=exited, status=0/SUCCESS) Main PID: 849 (spice-vdagentd) Tasks: 2 (limit: 4702) Memory: 944.0K CPU: 1.918s CGroup: /system.slice/spice-vdagentd.service └─849 /usr/sbin/spice-vdagentd Thanks and Best Regards Tom

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Re: how to change emulator path during live migration
by Peter Krempa 27 Apr '22

27 Apr '22

[re-adding libvirt-users list] Please always reply to the list so that the follow-up conversation is archived and delivered to all subscribers. On Wed, Apr 27, 2022 at 15:36:54 +0800, Jiatong Shen wrote: > Thank you for the feedback! > > Is it ok if the source node does not contain a emulator path used by the > dest node? for example, on src emulator path is /a/b/c, but > on dest it is /a/b/d, and /a/b/d does not exist on src. You can change the emulator path arbitrarily. The only limitation is that the emulator you pick (the binary, not the path) must be able to run the VM, but that will be validated during the migration.

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how to change emulator path during live migration
by Jiatong Shen 27 Apr '22

27 Apr '22

Hello libvirt experts, I am facing the following exceptions during live migrating a virtual machine from one compute node to another. file or directory: libvirt.libvirtError: Cannot check QEMU binary /usr/bin/kvm-spice: No such file or directory File "/var/lib/openstack/lib/python3.6/site-packages/eventlet/tpool.py", line 83, in tworker rv = meth(*args, **kwargs) File "/var/lib/openstack/lib/python3.6/site-packages/libvirt.py", line 1745, in migrateToURI3 if ret == -1: raise libvirtError ('virDomainMigrateToURI3() failed', dom=self) libvirt.libvirtError: Cannot check QEMU binary /usr/bin/kvm-spice: No such file or directory After some investigation, we found that this error is triggered because we do not have qemu-kvm installed in our container, btw the libvirt is directly installed on the source node. I have following questions Is it possible to change emulator during live migration? I try to to remove emulator under devices but looks like it does not help. thank you very much and looking forward for the feedback. -- Best Regards, Jiatong Shen

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set fixed time at vm guest startup?
by Fred Clift 26 Apr '22

26 Apr '22

I'm looking at the <clock> libvirt parameters. Is there a way to set the guests clock to a specific time/date at virt startup? I'm trying to virtualize a system with pci passthrough for a hardware device that wants to always live in pre-2011. The license manager for the software/hardware has 31-bit overflow of time calculations. The current process on the physical machine is to power it on, use the bios to set the hardware date to Jan 1 2010, boot the system, use an RC script to ntp-set the date now that the hardware is up and running, and then everything works till next boot. We even have a nice rc script that will set the clock back to 2010 if you do a clean shutdown/reboot. I see I can set my clock sync to variable and specify a negative offset - is there a way to just say "always be jan 10 2010 when you power on"? Fred

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discard option on ext4 mounts in QEMU qcow2 images
by Nate Collins 25 Apr '22

25 Apr '22

Hello, Does anyone have any real-world statistics on the reliability and performance of the ext4 discard option in QEMU VMs? I've heard it's discouraged for physical devices, as some are inefficient in how TRIM requests are processed, but I was wondering if there were any drawbacks/warnings when it comes to virtual disks (in this case, QCOW2s). I currently use either virtio-scsi or virtio-blk drivers for disk images depending on what the host/guest support, and run TRIMs weekly, but having an immediate freeing of space is desirable for many reasons. Also wondering if snapshots on snapshotting filesystems (such as ZFS) can run into corruption or other issues if snapshots are taken during a TRIM. Thanks.

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race condition? virsh migrate --copy-storage-all
by Valentijn Sessink 20 Apr '22

20 Apr '22

Hi list, I'm trying to migrate a few qemu virtual machines between two 1G ethernet connected hosts, with local storage only. I got endless "error: operation failed: migration of disk vda failed: Input/output error" errors and thought: something wrong with settings. However, then, suddenly: I succeeded without changing anything. And, hey: while ! time virsh migrate --live --persistent --undefinesource --copy-storage-all ubuntu20.04 qemu+ssh://duikboot/system; do a=$(( $a + 1 )); echo $a; done ... retried 8 times, but then: success. This smells like a race condition, doesn't it? A bit weird is the fact that the migration seems to succeed every time while copying from revolving disks to SSD; but the other way around has this Input/output error. There are some messages in /var/log/syslog, but not at the time of the failure, and no disk errors. These disks are LVM2 volumes and they live on raid arrays - and/so there is not a real, as in physical, I/O-error. Source system has SSD's, target system has regular disks. 1) is this the right mailing list? I'm not 100% sure. 2) how can I research this further? Spending hours on a "while / then" loop to try and retry live migration looks like a dull job for my poor computers ;-) Best regards, Valentijn

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Virtio-scsi and block mirroring
by Bjoern Teipel 19 Apr '22

19 Apr '22

Hello everyone, I’m looking at an issue where I do see guests freezing (Dl) process state during a block disk mirror from one storage to another storage (NFS) where the network stack of the guest can freeze for up to 10 seconds. Looking at the storage and IO I noticed good throughput ad low latency <3ms and I am having trouble to track down the source for the issue, as neither storage nor networking show issues. Interestingly when I do the same test with virtio-blk I do not really see the process freezes at the frequency or duration compared to virtio-scsi which seem to indicate a client side rather than storage side problem. I had looked at the syscalls and nothing stuck out: % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 28.51 20.672654 8339 2479 ioctl 27.81 20.162714 3379 5967 31 futex 22.02 15.964498 785 20335 poll 15.22 11.038403 150 73561 io_submit 4.17 3.023285 41 73540 lseek 1.20 0.868003 5 158591 write 0.63 0.459030 11 42871 ppoll 0.22 0.159263 8 19314 recvmsg 0.16 0.115520 5 22526 read 0.04 0.029149 29149 1 restart_syscall 0.01 0.009252 28 330 sendmsg 0.00 0.001221 1221 1 munmap 0.00 0.000458 22 21 fcntl 0.00 0.000286 95 3 openat 0.00 0.000166 5 32 rt_sigprocmask 0.00 0.000103 10 10 fdatasync 0.00 0.000099 25 4 clone 0.00 0.000081 7 12 mmap 0.00 0.000077 19 4 close 0.00 0.000076 6 12 mprotect 0.00 0.000056 14 4 madvise 0.00 0.000025 6 4 set_robust_list 0.00 0.000023 6 4 prctl ------ ----------- ----------- --------- --------- ---------------- 100.00 72.504442 419626 31 total Does anyone have an idea how to better debug this issue ? Thanks Bjoern

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When does the balloon-change or control-error event occur
by Han Han 19 Apr '22

19 Apr '22

Hi developers, I have questions about balloon-change or control-error event: 1. What's the meaning of these events 2. When do the events occur? The comments of their callbacks don't mention that( https://gitlab.com/libvirt/libvirt/-/blob/master/include/libvirt/libvirt-do… https://gitlab.com/libvirt/libvirt/-/blob/master/include/libvirt/libvirt-do… )

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Help with libvirt
by Eduardo Kiassucumuca 19 Apr '22

19 Apr '22

Good morning I'm Eduardo, a computer science student and I'm doing a final course work focused on virtualization. The work consists of creating virtual machines on a server and allowing ssh access to the virtual machines that are on the server containing qemu/kvm/libvirt. The problem is that I can't access the virtual machines from an external network but I can access them inside the server. I would like to know what would be the best way since we want to have a single public ip and be able to have a reverse proxy to access the virtual machines, I would like to know from your experience what you recommend?

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Libvirt vs QEMU benefits
by M, Shivakumar 19 Apr '22

19 Apr '22

Hello, For one of our case validation, we were using direct QEMU commands before for VM creation as it was easier to configure the VMs. Inside VM we do run the real-time latency test. Recently we switched to libvirt for the VM creation and deletion. Surprisingly, we do see a significant increase in the real-time latency performance for the VMs launched through the libvirt. W.r.t configuration wise both VMs are the same, we just converted the existing QEMU commands into libvirt XMLs. I am wondering what and all the features which libvirt has, improving this performance. Thanks, Shivakumar M

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Libvirt Daemon Question
by Michael Espinoza 13 Apr '22

13 Apr '22

Hi I’ve been googling this for a bit with no luck. Is there a way of determining what mode an already running libvirt daemon is running in.(session or system) From the docs it sounded like it was determined by what user started the daemon. But in a test node I set up, I have libvirtd running as root yet I can still connect to both the session and system qemus with virsh. And if I were to want libvirtd only in session mode, how would I do that? Thanks for the help! This stuff is really awesome and I’m just trying to get a full understanding of it. -Mike -- Michael Espinoza Mobile Phone : 646 327 9273 Email : Mikespinoza(a)gmail.com

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"default" watchdog device - ?
by lejeczek 08 Apr '22

08 Apr '22

Hi guys. Without explicitly, manually using watchdog device for a VM, the VM (centOS 8 Stream 4.18.0-365.el8.x86_64) shows '/dev/watchdog' exists. To double check - 'dumpxml' does not show any such device - what kind of a 'watchdog' that is? watchdog-5.15-2.el8.x86_64 on such a VM does not seem to do anything with it. Host is centOS 9 with: qemu-img-6.2.0-11.el9.x86_64 libvirt-daemon-8.0.0-5.el9.x86_64 many thanks, L.

3 6

Network interface element not working
by Ian Pilcher 05 Apr '22

05 Apr '22

I've added an interface element to a libvirt network, but it isn't working. The interface is not being added to the bridge, even after the system is rebooted. # virsh net-dumpxml ocp4-net <network> <name>ocp4-net</name> <uuid>b5852945-9889-4d22-ba61-879125316cec</uuid> <forward dev='eno2' mode='nat'> <nat> <port start='1024' end='65535'/> </nat> <interface dev='eno2'/> </forward> <bridge name='virbr-ocp4' stp='on' delay='0'/> <mac address='52:54:00:99:99:99'/> <ip address='192.168.123.1' netmask='255.255.255.0'> </ip> </network> # brctl show bridge name bridge id STP enabled interfaces virbr-ocp4 8000.525400999999 yes vnet0 virbr0 8000.525400a7ce7f yes virbr1 8000.52540051eb1f yes vnet1 # rpm -q libvirt libvirt-8.0.0-2.module_el8.6.0+1087+b42c8331.x86_64 Any ideas? -- ======================================================================== Google Where SkyNet meets Idiocracy ========================================================================

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Guest restarting after issuing a shutdown
by jonetsu 04 Apr '22

04 Apr '22

Hello everyone, I create kvm machines using a bash script. As expected from the script, the resulting virtual machines are performing as they should be. The aspect that I do not get is at the end of the creation, when issuing a 'shutdown now' in the guest and expecting that it will shut down. Instead it does shut down, but it is restarted immediately. The machines are created using an Arch Linux ISO file. The bash script runs in three stages, the first stage is on the host. virt-install will show the regular Arch Linux installation interface. The bash script is copied to the machine and its second stage is ran. After that a chroot is done and the third phase of the script is executed. When everything is configured and installed, here is what happens, commands are prefixed '%', text output is as is, and comments in '()' : guest : % shutdown now host : Domain creation completed. host : Restarting guest. (virt-manager shows the guest restarting) host : % virsh shutdown test02 (nothing happens, guest still shown) host : % virsh destroy test02 host : Domain test02 destroyed (guest display closes) What I'm expecting is that, when the 'shutdown now' is issued in the guest, that it will effectively terminate the guest, 'virsh list --all' will not show it running, and there'll be no need to issue a 'virsh destroy'. I have no clue at the moment why virsh is restarting the guest after a shutdown was issued in the guest. Looks like virsh did not get that it should terminate the guest and considers the shutdown as an error. Here are the versions involved : host : xubuntu 20.04 LTS libvirt 6.0.0-0ubuntu8.15 virt-manager 1:2.2.1-3ubuntu2.1 guest : archlinux 2022.03.01-x86_64 Thanks !

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Debugging hanging libvirt
by Tobias Hofmann (tohofman) 04 Apr '22

04 Apr '22

Hello all, I have a system with one VM running. After some time the VM needs to be temporarily stopped and started again. This start operation fails and from that point on any virsh command is hanging and does not execute. This issue is reproducible and I have already figured out that restarting libvirtd resolves this issue. However, I’m now trying to understand why it’s getting stuck in the first place. I try not to get too much into detail because I think this would be more confusing than it would actually help to understand the problem. In general, I’m wondering what approach you should follow to debug why libvirt gets stuck. Online I’ve read that you should run this command: `# gdb -batch -p $(pidof libvirtd) -ex 't a a bt f'`. I’ve run that command and attached the output to this mail. However, I have to admit that I have no idea what to do with it. System related info: * OS: CentOS 7.8.2003 * libvirt version: 4.5.0-33 Appreciate any help here! Thank you! Tobias

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