With QEMU version 3.1.50 (v3.1.0-1218-gad7a21e812-dirty) (commit ad7a21e81231ae64540310384fb0f87ac8758b02) on Xubuntu 18.04 host, a KDE Neon guest is crashing on boot. The QEMU command line is:
gdb -q -ex "set pagination off" -ex "set print thread-events off" -ex "handle SIGUSR1 nostop nopass noprint" -ex "run" --args qemu-system-x86_64 -accel kvm -cpu host -smp cores=2,threads=1 -m 2048 -hda neonbroken.qcow2 -cdrom ~/Downloads/neon-useredition-20190124-0530-amd64.iso -device qxl-vga,xres=1366,yres=768,addr=2 -display gtk,gl=on -monitor vc -serial vc -device qemu-xhci,addr=3 -netdev user,id=net0 -device e1000,netdev=net0,addr=4 -bios /usr/share/ovmf/OVMF.fd The crash is happening pretty frequently but not 100% of the times. Using virtio-vga instead of qxl-vga it's possible to use the guest normally. Before the crash there are some graphical artifacts on guest screen, they can be seen at https://i.imgur.com/rfTmmJ0.png On terminal QEMU prints the following messages: $ qemu-system-x86_64 -accel kvm -cpu host -smp cores=2,threads=1 -m 2048 -hda neonbroken.qcow2 -cdrom ~/Downloads/neon-useredition-20190124-0530-amd64.iso -device qxl-vga,xres=1366,yres=768,addr=2 -display gtk,gl=on -monitor vc -serial vc -device qemu-xhci,addr=3 -netdev user,id=net0 -device e1000,netdev=net0,addr=4 -bios /usr/share/ovmf/OVMF.fd (qemu-system-x86_64:11683): Gtk-WARNING **: 18:18:34.797: Theme parsing error: gtk.css:47:15: negative values are not allowed. id 0, group 0, virt start 0, virt end ffffffffffffffff, generation 0, delta 0 id 1, group 1, virt start 7ff31fe00000, virt end 7ff323dfe000, generation 0, delta 7ff31fe00000 id 2, group 1, virt start 7ff31bc00000, virt end 7ff31fc00000, generation 0, delta 7ff31bc00000 (qemu:11683): Spice-CRITICAL **: 18:39:40.747: memslot.c:111:memslot_get_virt: slot_id 255 too big, addr=ff000000ff000000 Abortado (imagem do núcleo gravada) Here is the backtrace: (gdb) bt #0 0x00007ffff0373e97 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51 #1 0x00007ffff0375801 in __GI_abort () at abort.c:79 #2 0x00007ffff1171cc9 in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #3 0x00007ffff11373b8 in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #4 0x00007ffff11407d0 in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #5 0x00007ffff1140a76 in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #6 0x00007ffff11419a1 in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #7 0x00007ffff11543cd in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #8 0x00007ffff1152d21 in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #9 0x00007ffff11534bf in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #10 0x00007ffff11214f1 in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #11 0x00007ffff1127d7b in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #12 0x00007ffff47931f5 in g_main_context_dispatch () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 #13 0x00007ffff47935c0 in () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 #14 0x00007ffff47938d2 in g_main_loop_run () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 #15 0x00007ffff1153b3a in () at /usr/lib/x86_64-linux-gnu/libspice-server.so.1 #16 0x00007ffff072d6db in start_thread (arg=0x7fff3602c700) at pthread_create.c:463