November 2016 - Users - libvirt List Archives

[libvirt-users] Sharing network namespace between containers
by Harish Vishwanath 08 Nov '16

08 Nov '16

Hello Based on the lxc driver documentation, I am trying to create an xml to share an existing network namespace with another container. I am running libvirt 1.2.15. Here is the xml: <domain type='lxc' xmlns:lxc='http://libvirt.org/schemas/domain/lxc/1.0'> <name>nt</name> <uuid>43c00192-e114-4e29-8ce7-4b5487f60a75</uuid> <memory unit='KiB'>65536</memory> <currentMemory unit='KiB'>65536</currentMemory> <vcpu placement='static'>1</vcpu> <cputune> <shares>2000</shares> </cputune> <resource> <partition>/apphosting.partition</partition> </resource> <os> <type arch='x86_64'>exe</type> <init>/sbin/init</init> </os> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <devices> <emulator>/usr/lib/libvirt/libvirt_lxc</emulator> <filesystem type='mount' accessmode='passthrough'> <source dir='/work/repo-lxc/nt/rootfs_mnt'/> <target dir='/'/> </filesystem> <filesystem type='mount' accessmode='squash'> <driver type='path' wrpolicy='immediate'/> <source dir='/local/local1/core_dir/nt'/> <target dir='/local/local1/core_dir'/> </filesystem>  <console type='pty'> <target type='lxc' port='0'/> </console> </devices> * <lxc:namespace>* * <lxc:sharenet type='netns' value='node'/>* * </lxc:namespace>* </domain> However, the virsh edit is unable to save this file: error: XML document failed to validate against schema: Unable to validate doc against /usr/share/libvirt/schemas/domain.rng Element domain has extra content: namespace Failed. Try again? [y,n,i,f,?]: Is this supported in libvirt 1.2.15 - the document doesnt specify a minimum version of libvirt. Appreciate your help. Regards, Harish

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[libvirt-users] virtual wlan0
by Michael Ströder 07 Nov '16

07 Nov '16

HI! My goal is to run a virtualized access point with hostapd. Is it possible to use the host's WIFI interface in a VM created with libvirt? I can add the interface in bridged mode but it appears just as normal eth1 without wireless extensions. Ciao, Michael.

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[libvirt-users] pci-assign fails with read error on config-space file
by Henning Schild 02 Nov '16

02 Nov '16

Hey, i am running an unusual setup where i assign pci devices behind the back of libvirt. I have two options to do that: 1. a wrapper script for qemu that takes care of suid-root and appends arguments for pci-assign 2. virsh qemu-monitor-command ... 'device_add pci-assign...' I know i should probably not be doing this, it is a workaround to introduce fine-grained pci-assignment in an openstack setup, where vendor and device id are not enough to pick the right device for a vm. In both cases qemu will crash with the following output: > qemu: hardware error: pci read failed, ret = 0 errno = 22 followed by the usual machine state dump. With strace i found it to be a failing read on the config space file of my device. /sys/bus/pci/devices/0000:xx:xx.x/config A few reads out of that file succeeded, as well as accesses on vendor etc. Manually launching a qemu with the pci-assign works without a problem, so i "blame" libvirt and the cgroup environment the qemu ends up in. So i put a bash into the exact same cgroup setup - next to a running qemu, expecting a dd or hexdump on the config-space file to fail. But from that bash i can read the file without a problem. Has anyone seen that problem before? Right now i do not know what i am missing, maybe qemu is hitting some limits configured for the cgroups or whatever. I can not use pci-assign from libvirt, but if i did would it configure cgroups in a different way or relax some limits? What would be a good next step to debug that? Right now i am looking at kernel event traces, but the machine is pretty big and so is the trace. That assignment used to work and i do not know how it broke, i have tried combinations of several kernels, versions of libvirt and qemu. (kernel 3.18 and 4.4, libvirt 1.3.2 and 2.0.0, and qemu 2.2.1 and 2.7) All combinations show the same problem, even the ones that work on other machines. So when it comes to software versions the problem could well be caused by a software update of another component, that i got with the package manager and did not compile myself. It is a debian 8.6 with all recent updates installed. My guess would be that systemd could have an influence on cgroups or limits causing such a problem. regards, Henning

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[libvirt-users] pass-through hwrng
by lejeczek 02 Nov '16

02 Nov '16

hi all I have in my centos 7 this: crw-------. 1 root root 10, 183 Oct 11 21:28 /dev/hwrng and VM fails, complains like this: virsh # start volatile-work6 error: Failed to start domain volatile-work6 error: internal error: process exited while connecting to monitor: 2016-10-19T09:42:05.988142Z qemu-kvm: -object rng-random,id=objrng0,filename=/dev/hwrng: Could not open '/dev/hwrng': Permission denied which reads logical. Now - is this normal that hwrng is created with these permissions? And if yes then how to pass-through it to the VMs? How to aid VMs with hardware random numbers generator? many thanks. L

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