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Re: [libvirt-users] Slow boot when no serial pty connected



On Tue, Dec 15, 2015 at 09:47:41PM +0100, David Caro wrote:

Hi everyone!

It's the first time I send a message to this list, I hope it's not the last :)

So my issue is that when booting a disk image generated with virt-builder [1]
it takes more than 5 minutes, waiting in the boot screen that says:

"
Booting from disk...
press any key to continue.
"

The press any key message shows up to 5 times. The issue is that it stays in
that screen for more than 5 min.

If I attach a serial pty device, then it takes ~5 seconds to go through that
screen (same messages, just show faster).


This sounds like a bug.  If that is the case, then it could be QEMU's
problem, for that I would suggest asking on qemu-discuss:

 https://lists.nongnu.org/mailman/listinfo/qemu-discuss

If, however, that is expected, for some reason, then virt-builder could
add the pty itself.  For that I would ask on libguestfs ML:

 https://www.redhat.com/mailman/listinfo/libguestfs

I would add those lists to Cc, but cross-posting through 3 lists does
not sound like a great idea.  But the chance that someone from qemu and
libguestfs will have a look at this is quite low here I guess.

I don't want to have to create a pty device each time I want to spin up a vm
(if there's a way to tell libvirt to do that for me that would be ok too).


You could use virt-xml from the virt-tools (installed as part of
virt-manager, I believe) to do that:

 virt-xml fedora23 --add-device --serial pty

Is there any workaround I can do to avoid having to create a pty and still get
fast boot?


The xml of the slow vm:

<domain type='kvm'>
   <name>fedora23</name>
   <memory unit='MiB'>2048</memory>
   <vcpu>1</vcpu>
   <cpu mode='host-passthrough'>
     <topology sockets='1' cores='1' threads='1'/>
   </cpu>
   <os>
     <type arch='x86_64' machine='pc'>hvm</type>
     <boot dev='hd'/>
     <bootmenu enable='yes' timeout='3000'/>

This should mean that qemu will wait in the boot menu for 3 seconds and
then it continue booting from hard drive first.  Can you try removing
this form the XML (using virsh edit for example) or just set enable to
"no"?  Just to see whether it's misbehaving as well.

If contacting the qemu mailing list, I suggest attaching the command
line htat's used for qemu to run.

   </os>
   <features>
     <acpi/>
     <apic/>
     <pae/>
   </features>
   <devices>
     <emulator>/usr/libexec/qemu-kvm</emulator>
     <disk type='file' device='disk'>
       <driver name='qemu' type='qcow2'/>
       <source file='/tmp/fedora-23.qcow2'/>
       <target dev='sda' bus='virtio'/>
     </disk>
     <graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0' keymap='en-us'/>
     <channel type='unix'>
       <source mode='bind'/>
       <target type='virtio' name='org.qemu.guest_agent.0'/>
     </channel>
   </devices>
</domain>


The same with this device boots fast:

   <serial type='pty'>
     <source path='/dev/pts/12'/>
     <target port='0'/>
     <alias name='serial0'/>
   </serial>


The libvirt/qemu/kvm versions I'm using:

ipxe-roms-qemu-20150407-3.gitdc795b9f.fc23.noarch
libvirt-1.2.18.1-2.fc23.x86_64
libvirt-client-1.2.18.1-2.fc23.x86_64
libvirt-daemon-1.2.18.1-2.fc23.x86_64
libvirt-daemon-config-network-1.2.18.1-2.fc23.x86_64
libvirt-daemon-config-nwfilter-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-interface-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-libxl-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-lxc-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-network-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-nodedev-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-nwfilter-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-qemu-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-secret-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-storage-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-uml-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-vbox-1.2.18.1-2.fc23.x86_64
libvirt-daemon-driver-xen-1.2.18.1-2.fc23.x86_64
libvirt-daemon-kvm-1.2.18.1-2.fc23.x86_64
libvirt-gconfig-0.2.2-1.fc23.x86_64
libvirt-glib-0.2.2-1.fc23.x86_64
libvirt-gobject-0.2.2-1.fc23.x86_64
libvirt-python-1.2.18-1.fc23.x86_64
qemu-common-2.4.1-1.fc23.x86_64
qemu-guest-agent-2.4.1-1.fc23.x86_64
qemu-img-2.4.1-1.fc23.x86_64
qemu-kvm-2.4.1-1.fc23.x86_64
qemu-system-x86-2.4.1-1.fc23.x86_64


Thanks!!


[1] The image was created with the command:
 $ virt-builder --format=qcow2 fedora-23


--
David Caro

Red Hat S.L.
Continuous Integration Engineer - EMEA ENG Virtualization R&D

Tel.: +420 532 294 605
Email: dcaro redhat com
IRC: dcaro|dcaroest {freenode|oftc|redhat}
Web: www.redhat.com
RHT Global #: 82-62605



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