Questions tagged [virtual-machine]

A virtual machine (VM) is a guest Operating System running in a completely isolated environment within a normal host operating system. Modern virtual machines are implemented with either software emulation or hardware virtualization or (in most cases) both together.

522 questions with no upvoted or accepted answers
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12
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9k views

Performance comparison of e1000 and virtio-pci drivers

I made a following setup to compare a performance of virtio-pci and e1000 drivers: I expected to see much higher throughput in case of virtio-pci compared to e1000, but they performed identically. ...
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2answers
3k views

virNetSocketReadWire:1801 : End of file while reading data: Input/output error

Every time I start/stop a KVM, the libvirtd 3.0.0-4 throws the following error in syslog: libvirtd[3145]: 2018-08-07 21:00:19.699+0000: 3145: \ error : qemuMonitorIO:710 : internal error: \ ...
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Virtualization (KVM) and excessive cached RAM

I've set up a virtual machine through KVM-libvirt (virt-manager) with Windows 10 on it and I'm getting an odd behavior on the host side. I'm running a 64bit Arch host with 24GB of RAM, 12 of which are ...
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472 views

How do I actually make use of the kvm-clock clock driver?

According to copious sources, the KVM clock driver is loaded as shown here: cat /sys/devices/system/clocksource/clocksource0/current_clocksource These sources all seem to think that this ...
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0answers
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perf cycles not supported

I am trying to use perf for profiling in a Linux virtual machine. However, I am receiving the following output: [vagrant@localhost ~]$ perf stat -d ls / bin boot dev etc home lib lib64 lost+...
5
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2answers
883 views

On Linux, (how) can I “hot-unplug” memory?

This is what I've tried: sudo zsh -c 'echo offline >/sys/devices/system/memory/memory109/state'` and got the following error: zsh:echo:1: write error: device or resource busy Do I perhaps need ...
4
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0answers
2k views

Unable to successfully setup bridge interface with Netplan, in order to support guest OS with KVM

First of all, I would like to apologize for my bad English. I usually find an answer after a few hours, days or even weeks of research, but today, I feel quite lost and would appreciate some help. ...
4
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1answer
773 views

How to convert root filesystem to virtual disk format (img, vmdk or vdi)?

I unpacked the contents of a Mageia 6 ISO image, including a Linux root file system in it, and I've updated the root file system by chrooting into it and running dnf update. I also installed a few ...
4
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1answer
201 views

Disable buffering in a VM configuration

I am executing some benchmark using a DBMS and virtual machines. And I am using this command free && sync && echo 3 > /proc/sys/vm/drop_caches && free on each Guest, and ...
4
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0answers
227 views

sharing folders in virtual box

I'm trying to run a Linux Mint guest inside a Linux Mint host(both 64-bit). I've installed Guest Additions etc. But I'm not able to access the shared folder. sudo mount -t vboxsf kernel /media/...
4
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0answers
5k views

In virtual machine manager, is there a way to add disk space to an existing disk?

I know that in virt-manager you can add RAM and processors to the virtual machine, but is there a way to increase the available disk space larger through the GUI? Edit: @slm was able to find the ...
3
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0answers
16 views

Setting up a virtual server group with a bridged interface

I posted a specific problem with DHCP over virtual network components here, but it is quite specific and does not cover the larger problem I would like to address. I have a physical server and want to ...
3
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0answers
134 views

Oracle VirtualBox for Ubuntu detecting avx & avx2 for one CPU but not the other

I have been looking into this issue for days now. In short, Oracle VirtualBox started supporting avx & avx2 since version 5.0.3. Right now, it's on 6.1.16, so way ahead. I had many problems ...
3
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0answers
1k views

nested virtualization (Intel VT-x) with qemu on mac osx versus linux

I know that kvm-qemu supports nested virtualization for Intel (VT-x) on Linux, since I have this working. I don't have this working on my mac with os x as a host though. My Macbook Air with Dual-...
3
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0answers
603 views

Forward iOS Tablet from Linux Desktop to QEMU macOS VM

I am running macOS 15 in a qemu virtual machine on a manjaro Linux machine. Since I want to use it for iOS development/deployment I tried connecting and forwarding an iPad running the latest iPad-OS ...
3
votes
1answer
2k views

How to route traffic through VPN only accessible within VM (without a bridged adapter)?

I have an interesting situation where I have a corporate VPN that can only connect through a specific (outdated) version of Ubuntu (and/or Windows) using a vendor-supplied client that creates a VPN ...
3
votes
1answer
2k views

VMs attached to the same bridge cannot ping each other

I am now trying to host two VMs directly by qemu, without any tools like libvirt. I did setup the bridge/tap interfaces for each of them like ip link add br0 type bridge ip addr add 192.168.122.1/24 ...
3
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0answers
335 views

FreeBSD/OVS equivalent of ESXi vSwitch VLAN config

I'm trying out FreeBSD with bhyve hypervisor and trying to replicate VMware ESXi vSwitch config in FreeBSD so that pfSense VM gets network traffic properly. VLANs: 111 = LAN, 192.168.101.0/24 333 = ...
3
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0answers
926 views

KVM passthrough in virtual machine more than 3 usb devices

I have a question, how can i passthrough in virtual machine more than 3 usb devices? I have a usb hub and i cannot passthrough in virtual machine more than 3 usb device. My usb device connect to usb ...
3
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0answers
6k views

AMD-Vi: Unable to write to IOMMU perf counter. Arch Linux

I'm having some problems with an Antergos 4.18 installation on my Acer Swift 3 (SF315-41) the main one is regarding virtualization. At first when I booted up the OS I would get this messages: [...
3
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0answers
950 views

Rename qcow2 internal snapshots created with virsh snapshot-create-as

Background I have a QEMU/KVM virtual machine whose virtual disk is a qcow2 file. To create snapshots, I have been using sudo virsh snapshot-create-as <vm_name> <snapshot_name> and now I ...
3
votes
1answer
2k views

QEMU Guest using huge amounts of compressed memory on boot

Virt Manager configuration: Guest memory usage right after booting (nothing is running): I'm running virt-manager on a standard Ubuntu 17.10 system. In Proxmox, the same general configuration (with ...
3
votes
0answers
79 views

How is the cgroup user UID of a container's user allocated?

I use containers (systemd-nspawn but I believe lxc will be similar) and from the perspective of the host, users in containers (including root) have specific UIDs, such as 3804364+. Are these IDs ...
3
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0answers
145 views

how to update the firmware of an epson xp 211 printer in linux?

Since the epson utility are available for windows and mac, I was wondering how to update the firmware in Linux. Comment> Using a virtualized windows/mac machine would work?. I remembered , this was ...
3
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0answers
1k views

How to define multiple routes for KVM guests with CentOS 7

The code below generates two CentOS 7 GUEST virtual machines on a CentOS 7 HOST. One of the virtual machines is connected to the internet via a PUBLIC IP address. The other is given a PRIVATE IP ...
3
votes
1answer
3k views

How do I assign static IPs for HOST, BRIDGE, and GUEST

I am learning networking by building a small virtual network within a CentOS host. I need some guidance at the highest level to start planning: The Scenario: A CentOS 7 HOST needs to have a ...
3
votes
0answers
427 views

KVM/QEMU hot-replace raw disk

One of VM disks got damaged and I'm trying to replace it online, without rebooting VM. However when I use: drive_add virtio1 file=/dev/sdb,format=raw,if=virtio,cache=none,aio=native in VM monitor ...
3
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0answers
703 views

*REAL* zerofree equivalent for btrfs

is there any zerofree equivalent for btrfs ? and please don't give me sfill or cat /dev/zero >/tmp/file, this is not the same thing at all, be cause Zerofree finds the unallocated, non-zeroed blocks, ...
3
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0answers
95 views

Why does bash appear faster on an Ubuntu VM than on the host MacOS?

This is the laptop sitting in front of me right now: On it is installed VMWare Fusion 8.5.3 with an Ubuntu 16.04 64 bit VM. I ran the following little test to compare performance between bash on the ...
3
votes
0answers
333 views

Logitech controller not passing into Centos virtual machine as joystick

I have a Logitech Dual Action Controller that I am trying to use in a Centos virtual machine (using VirtualBox). The controller is in "D" mode (according to the switch on the back of the controller) ...
3
votes
0answers
270 views

How to tell virsh: save state of VM and vdisk, but not attached disk?

I installed a fresh CentOS 7.2 guest (babybrighton) on my host (brighton), and then did this from brighton (where /dev/sdb is a physical device connected to brighton): virsh attach-disk --...
3
votes
2answers
433 views

Verifying IO bottleneck

We are working on a project to benchmark systems in virtual machines that share the same physical host. I think we have a bottleneck with the system hosting the virtual machines, which may ...
3
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0answers
8k views

Libvirt qemu changing hardware identifiers?

I am having a strange problem that I just cannot figure out. I have a Windows 7 virtual machine that was originally a physical machine that was demoted to a VM awhile ago. I used to boot it with ...
3
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0answers
601 views

Is there a more efficient way of defragmenting Linux memory other than rebooting?

I am running Gentoo Linux with kernel 4.4.8-hardened-r1, QEMU-KVM version 2.5.1 and 3227 MB of system-visible RAM (without considering RAM taken by BIOS and my AMD APU's graphics). I have a VM that ...
3
votes
1answer
600 views

Getting a Windows 7 installation to run virtualized under Ubuntu?

I've currently installed Windows 7 and Ubuntu via dualboot. To avoid switching the OS by rebooting, i want to be able to start my Windows 7 via a virtual machine. It is important to be able to boot ...
3
votes
0answers
1k views

Virtualbox and GPU Pass-trough: Device with host PCI address already attached to this VM

I have server with several GPUs. My idea is to attach them to different VMs in order to use that VMs in CUDA (or OpenCL) calculations. My setup: CPU: Intel Xeon E5-2670 GPUs: 1 x Radeon HD 7970 $ ...
3
votes
1answer
591 views

Iptables rule to drop packets to and from local network

I want to set a virtual machine on laptop, but I don't trust the guest system fully, so I would like to block it's access to local network (to network 192.168.0.1/16 or 10.0.0.1/8 or ... the other one ...
3
votes
0answers
995 views

Running Mac OS X under KVM/QEMU

Note to be removed in the future, so as to avoid confusion from answerers and mods edit: Forgot to add in the note, if anyone thinks this is the wrong stack-site to post this, please comment on why, ...
3
votes
1answer
676 views

Arch Linux openSSH frequently drops connection

I'm running a VM using Oracle's VirtualBox. The OS is the latest version of Arch, 64-bit. For some odd reason, every so often (frequently enough to be very annoying and making it almost impossible ...
3
votes
0answers
1k views

Network connectivity issue between different hosts from a network namespace in one host

I have created two Ubuntu 12.04 VMs using VMWare Player with NAT network configuration. I am able to ping them from each other. After that, I created a network namespace in one of them and add a ...
2
votes
0answers
149 views

setxkbmap -option ctrl:nocaps does not map Caps Lock to Escape inside Debian VM running in Oracle VirtualBox on macOS

I am using Xfce 4.12 on Debian 10 running inside Oracle VirtualBox 6.1 running on macOS Catalina. All my key mappings are set to default on macOS. (System Preferences > Keyboard > Modifier Keys &...
2
votes
0answers
22 views

Intermittent connectivity to a SunOS 4.1.4 virtual machine

I am running SunOS 4.1.4 (those were the days...) under QEMU, networked via a tap device on the host. I'm starting the vm like this... qemu-system-sparc \ -rtc base=utc \ -drive file=sunos-...
2
votes
1answer
79 views

Cannot install Cinnamon on Debian. Is this environment compatible with it?

One year and half ago, I tried to install my new Debian 9 computer with Cinnamon : it failed and froze at installation. Because I had no Linux knowledge I installed Gnome instead. Today, I am on ...
2
votes
0answers
45 views

Is it possible to delete files on linux before exporting it like virtual machine?

I know that before exporting a virtual machine you need to shutdown the guest OS. I need to delete a file on the system before exporting the machine or after importing it and starting of loading the ...
2
votes
0answers
463 views

XAUTHORITY environment value is not a clean path

I am having trouble opening VS Code from my VM running on Ubuntu 16.04. When I try to open it from the terminal, I get the error: WARNING: XAUTHORITY environment value is not a clean path: "/some/...
2
votes
2answers
2k views

How to enable an Ethernet interface at boot on CentOS 8?

I have a VM which is connected to a network with DHCP etc. Whenever I boot the VM the virtual Ethernet connection is DOWN. I need to log in by console and run dhclient eth0 to enable it. Every time....
2
votes
0answers
158 views

Smooth Linux VM (VirtualBox) on Windows 10?

I need to create a Virtual Machine running a Linux-based OS. I have tried with Ubuntu 16.04 LTS and 18.04 LTS. The problem that I can't help having is that its interface is laggy and slow in terms of ...
2
votes
1answer
553 views

Part of virtual machine's screen is not visible when resolution changes with SPICE

A virtual machine with Windows 10 as the guest's OS is set up using KVM/QEMU. Without SPICE, it worked perfectly fine but for clipboard sharing, I followed Arch Linux's Guide. But then it's super ...
2
votes
1answer
587 views

Virtualize in multiple TTY (VT*)

I want to get virtual machine in a TTY (VT*) in fullscreen like GDM3 can take a TTY (VT*) for the graphic part of linux I want DISPLAY (heard as the output of a graphic server, here the VMs) to be ...

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