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

[Olivier Mauras]

> 
> 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 /srv/overlay/kernels/grsec-3.14.33-101/vmlinuz-3.14.33-101.el6.x86_64 \
> 
> -initrd /srv/overlay/kernels/grsec-3.14.33-101/initramfs-3.14.33-101.el6.x86_64.img \
>   -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 config:
> <domain type='kvm'>
>   <name>irc</name>
>   <uuid>ffbd32eb-a693-eadd-8923-18de80137472</uuid>
>   <memory unit='KiB'>262144</memory>
>   <currentMemory unit='KiB'>262144</currentMemory>
>   <vcpu placement='static'>1</vcpu>
>   <os>
>     <type arch='x86_64' machine='pc-i440fx-2.1'>hvm</type>
> 
> <kernel>/srv/overlay/kernels/grsec-3.14.33-101/vmlinuz-3.14.33-101.el6.x86_64</kernel>
> 
> <initrd>/srv/overlay/kernels/grsec-3.14.33-101/initramfs-3.14.33-101.el6.x86_64.img</initrd>
>     <cmdline>root=virtfs:root rootflags=trans=virtio,version=9p2000.u
> ro rootfstype=9p</cmdline>
>     <boot dev='hd'/>
>   </os>
>   <features>
>     <acpi/>
>     <apic/>
>     <pae/>
>   </features>
>   <clock offset='utc'/>
>   <on_poweroff>destroy</on_poweroff>
>   <on_reboot>restart</on_reboot>
>   <on_crash>restart</on_crash>
>   <devices>
>     <emulator>/usr/bin/qemu-system-x86_64</emulator>
>     <controller type='usb' index='0'>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x01'
> function='0x2'/>
>     </controller>
>     <controller type='pci' index='0' model='pci-root'/>
>     <filesystem type='mount' accessmode='passthrough'>
>       <source dir='/srv/overlay/run/irc'/>
>       <target dir='root'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
> function='0x0'/>
>     </filesystem>
>     <interface type='bridge'>
>       <mac address='52:54:00:00:36:34'/>
>       <source bridge='br0'/>
>       <model type='virtio'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x03'
> function='0x0'/>
>     </interface>
>     <serial type='pty'>
>       <target port='0'/>
>     </serial>
>     <console type='pty'>
>       <target type='serial' port='0'/>
>     </console>
>     <input type='mouse' bus='ps2'/>
>     <input type='keyboard' bus='ps2'/>
>     <graphics type='vnc' port='-1' autoport='yes'/>
>     <video>
>       <model type='cirrus' vram='9216' heads='1'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x02'
> function='0x0'/>
>     </video>
>     <memballoon model='virtio'>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x04'
> function='0x0'/>
>     </memballoon>
>   </devices>
> </domain>
> 
> 
> My libvirt version is 1.2.9, and qemu is 2.1.2.
> 
> Thanks for your help,
> 
> Olivier
> 
>  
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> libvirt-users mailing list
> libvirt-users at redhat.com
> https://www.redhat.com/mailman/listinfo/libvirt-users

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 ?

Thanks,
Olivier
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