PID: 0.106
network: 0.091
device: 0.079
socket: 0.073
permissions: 0.073
other: 0.073
performance: 0.071
boot: 0.067
vnc: 0.066
semantic: 0.065
graphic: 0.063
debug: 0.060
files: 0.057
KVM: 0.056
boot: 0.335
PID: 0.283
debug: 0.190
socket: 0.054
KVM: 0.037
files: 0.018
vnc: 0.015
other: 0.015
device: 0.015
performance: 0.013
network: 0.009
semantic: 0.007
permissions: 0.004
graphic: 0.004

Hosts fail to start after update to QEMU 3.0

Host OS: Archlinux
Host Architecture: AMD64
Guest OS: FreeBSD-11.2 (x2) and Archlinux (x1)
Guest Architecture: AMD64

I have been using QEMU 2.x without issue for a number of years but since updating to QEMU 3.0 my guests do not complete startup.

FreeBSD 11.2 guest failure symptom:
The two FreeBSD-11.2 guests output repeated messages of "unexpected cache type 4". This appears to be an internal error message and I've not found any instances of it through Google search.

Archlinux guest failure symptom:
The single Archlinux guest gets no further than the message "uncompressing initial ramdisk".

The guests are started by a qemu-kvm invokation. No virtual machine managers are used. The command lines used (from ps awx) to launch the VMs are:

[neil@optimus ~]$ ps awx |grep qemu
 1492 ?        Sl     3:19 /usr/bin/qemu-system-x86_64 -daemonize -pidfile /run/qemu_vps1.pid -enable-kvm -cpu host -smp 2 -k en-gb -boot order=c -drive file=/dev/system/vps1,cache=none,format=raw,if=virtio,index=0,media=disk -m 1024 -name FreeBSD_1 -net nic,macaddr=52:54:AD:86:64:00,model=virtio -net vde,sock=/run/vde_switch-tap0.sock -monitor telnet:127.0.0.2:23,server,nowait -vnc 192.168.0.1:0
 1510 ?        Sl     0:54 /usr/bin/qemu-system-x86_64 -daemonize -pidfile /run/qemu_vps2.pid -enable-kvm -cpu host -smp 2 -k en-gb -boot order=c -drive file=/dev/system/vps2,cache=none,format=raw,if=virtio,index=0,media=disk -m 1024 -name Archlinux -net nic,macaddr=52:54:AD:86:64:01,model=virtio -net vde,sock=/run/vde_switch-tap0.sock -monitor telnet:127.0.0.3:23,server,nowait -vnc 192.168.0.1:1
 1529 ?        Sl     3:07 /usr/bin/qemu-system-x86_64 -daemonize -pidfile /run/qemu_vps3.pid -enable-kvm -cpu host -smp 2 -k en-gb -boot order=c -drive file=/dev/system/vps3,cache=none,format=raw,if=virtio,index=0,media=disk -m 1024 -name FreeBSD_2 -net nic,macaddr=52:54:AD:86:64:02,model=virtio -net vde,sock=/run/vde_switch-tap0.sock -monitor telnet:127.0.0.4:23,server,nowait -vnc 192.168.0.1:2

The VMs were installed to LVM volumes on the host machine (hence the /dev/system/vpsN device names). Networking is over a Linux tap interface connected to a VDE2 virtual network switch.

Currently working version of QEMU: qemu-headless 2.12.1-1
Failing version of QEMU: qemu-headless-3.0.0-1

Archlinux have released qemu-headless-3.0.0-3 which includes a backported patch for virtio. I have tested this version and the problem still persists.

This bug is not present in QEMU-3.1.0.

Ok, thanks for the update. Closing this bug since it seems to be fixed in 3.1.