[libvirt-users] Broken OS when booting rootfs from 9p share

Olivier Mauras olivier at mauras.ch
Mon Mar 2 13:13:16 UTC 2015


Finally got it working by setting user root as qemu user and
disabling clearing of capabilities.


On 2015-02-26 17:49,
Olivier Mauras wrote: 

> On 2015-02-26 17:05, Kashyap Chamarthy wrote:

>> On Tue, Feb 24, 2015 at 11:56:50PM +0100, Olivier Mauras
>>> On Tue, 2015-02-24 at 16:05 -0500, Laine Stump wrote:

>>>> On 02/24/2015 03:37 PM, Olivier Mauras wrote: 
Hello, I've been trying to boot a VM with the rootfs being a 9P share
from the host. The VM OS is centos 7. The OS boots but no services can
work and it appears that the authentication system is broken. Now the
funny thing is that booting the same OS on the same 9P share manually
with Qemu works as expected with a fully functionnal OS... So I'm
wondering what could libvirt do that render the OS on the share broken -
Something with rights ? Selinux is disabled on the host, and accessmode
to the share is set to passthrough in both cases. Here's my working Qemu
line: qemu -kernel
-fsdev local,id=r,path=/srv/overlay/run/irc,security_model=passthrough
-device virtio-9p-pci,fsdev=r,mount_tag=root -nographic -m 256M -machine
pc-i440fx-2.1,accel=kvm -netdev tap,id=net0 -device
virtio-net,netdev=net0,mac=52:54:00:12:36:34 -smp 1,sockets=1,cores=1
-append 'root=virtfs:root rootflags=trans=virtio,version=9p2000.u ro
rootfstype=9p console=ttyS0' And here my libvirt VM
rootflags=trans=virtio,version=9p2000.u ro
rootfstype=9pdestroyrestartrestart/usr/bin/qemu-system-x86_64 My libvirt
version is 1.2.9, and qemu is 2.1.2. Thanks for your help, Olivier
_______________________________________________ libvirt-users mailing
list libvirt-users at redhat.com [1]
https://www.redhat.com/mailman/listinfo/libvirt-users [2]
>>>>> So I
updated libvirt to 1.2.12 and qemu to 2.1.3 and it still gives me the
exact same behaviour ... Could it be that the share was created with an
old version of virt-manager redenring in old/broken XML? From Qemu
config example i don't see how my XML could be incorrect. Any idea
>>>> I know nothing about the 9p filesystem, but since you have a qemu
commandline that works and a libvirt config that doesn't, the next
logical step would be to provide the non-working qemu commandline
generated by libvirt. You can find this at the end of the log file
>>> Here it is... A bit more complex :)
LC_ALL=C PATH=/sbin:/usr/sbin:/bin:/usr/bin QEMU_AUDIO_DRV=none
/usr/bin/qemu-system-x86_64 -name irc -S -machine
pc-i440fx-2.1,accel=kvm,usb=off -m 256 -realtime mlock=off -smp
1,sockets=1,cores=1,threads=1 -uuid ffbd32eb-a693-eadd-8923-18de80137472
-no-user-config -nodefaults -chardev
-mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc
-no-shutdown -no-acpi -boot strict=on -kernel
-append root=virtfs:root rootflags=trans=virtio,version=9p2000.u rw
rootfstype=9p -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2
-netdev tap,fd=27,id=hostnet0,vhost=on,vhostfd=28 -device
-chardev pty,id=charserial0 -device
isa-serial,chardev=charserial0,id=serial0 -vnc -device
cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device
virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 -msg timestamp=on

>> Maybe you can try enabling Debug logs/filters in libvirt
>> and see if that helps you
narrow down?
> #!/bin/bash
PATH=/sbin:/usr/sbin:/bin:/usr/bin QEMU_AUDIO_DRV=none
/usr/bin/qemu-system-x86_64 -name irc -machine pc-i440fx-2.1,accel=kvm
-m 256 -smp 1,sockets=1,cores=1,threads=1 
> -no-user-config 
> -chardev
-mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -boot
> -kernel

> -append 'root=virtfs:root rootflags=trans=virtio,version=9p2000.u rw
rootfstype=9p console=ttyS0' 
> -fsdev
> -device

> -chardev stdio,id=charserial0 -device
isa-serial,chardev=charserial0,id=serial0 -device
cirrus-vga,id=video0,bus=pci.0,addr=0x3 -device
virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 -msg timestamp=on
This gives me the same result as my first qemu command. Seems that
-nodefaults gives me non booted state VM.


mailto:libvirt-users at redhat.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/libvirt-users/attachments/20150302/2bfe65ba/attachment.htm>

More information about the libvirt-users mailing list