Control: tag -1 + moreinfo
14.02.2025 04:02, Wakko Warner wrote:
Package: qemu-system-x86
Version: 1:9.2.0+ds-5
Severity: normal
I recently upgraded qemu to this version (9.2.0+ds-5) and the console no longer
shows anything. I normally run qemu with libvirt and virt-manager.
To rule out upgraded libvirt, I tried launching qemu with similar options as
libvirt did and -display gtk. I still get the same blackscreen. Appears that
keyboard input works, when pressing enter, the vm starts booting and once the
video driver loads, I'm able to see text and graphics. This works for both
libvirt and standalone.
I tried to change from qxl-vga to VGA and cirrus-vga with the same results.
If I downgrade to 9.0.2+ds-7 it works as expected with both
libvirt/virt-manager and launching qemu directly.
The first version to cause this issue is 9.1.0+ds-2 (I could not find -1)
This is interesting. It works for me exactly the same with current 9.2.x and
with all older releases too.
The system has been fully updated to latest sid as of 20250211 except for a
few python libraries and virt-manager.
This is an example of the command used to launch qemu standalone:
/usr/bin/qemu-system-x86_64 \
-name guest=box,debug-threads=on \
-S \
-machine pc-q35-7.2,usb=off,dump-guest-core=off,acpi=on \
-accel kvm \
-cpu qemu64 \
-m size=4194304k \
-overcommit mem-lock=off \
-smp 2,sockets=1,dies=1,clusters=1,cores=2,threads=1 \
-uuid 538bc7fc-9a8f-40ec-884f-2a870e74478b \
-no-user-config \
-nodefaults \
-rtc base=utc \
-no-shutdown \
-boot menu=on,strict=on \
-device
'{"driver":"pcie-root-port","port":16,"chassis":1,"id":"pci.1","bus":"pcie.0","multifunction":true,"addr":"0x2"}'
\
-device
'{"driver":"pcie-root-port","port":17,"chassis":2,"id":"pci.2","bus":"pcie.0","addr":"0x2.0x1"}'
\
-device
'{"driver":"pcie-root-port","port":18,"chassis":3,"id":"pci.3","bus":"pcie.0","addr":"0x2.0x2"}'
\
-device '{"driver":"qemu-xhci","id":"usb","bus":"pci.1","addr":"0x0"}' \
-device '{"driver":"virtio-scsi-pci","id":"scsi0","bus":"pcie.0","addr":"0x4"}'
\
-device
'{"driver":"virtio-serial-pci","id":"virtio-serial0","bus":"pcie.0","addr":"0x7"}'
\
-blockdev
'{"driver":"file","filename":"/vm/box.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap","cache":{"direct":true,"no-flush":false}}'
\
-blockdev
'{"node-name":"libvirt-1-format","read-only":false,"discard":"unmap","detect-zeroes":"unmap","cache":{"direct":true,"no-flush":false},"driver":"qcow2","file":"libvirt-1-storage","backing":null}'
\
-device
'{"driver":"scsi-hd","bus":"scsi0.0","channel":0,"scsi-id":0,"lun":0,"device_id":"drive-scsi0-0-0-0","drive":"libvirt-1-format","id":"scsi0-0-0-0","bootindex":1,"write-cache":"on"}'
\
-device '{"driver":"usb-tablet","id":"input2","bus":"usb.0","port":"1"}' \
-audiodev '{"id":"audio1","driver":"none"}' \
-device
'{"driver":"qxl-vga","id":"video0","max_outputs":1,"ram_size":67108864,"vram_size":67108864,"vram64_size_mb":0,"vgamem_mb":16,"bus":"pcie.0","addr":"0x1"}'
\
-global ICH9-LPC.noreboot=off \
-watchdog-action reset \
-sandbox
on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
-msg timestamp=on \
-display gtk
This command line is problematic. You request qemu to start the
guest in paused mode (-S), so it (correctly) shows the black screen.
And you don't specify a monitor where you can ask qemu to actually
start the virtual CPU. So it will stay paused forever until you
terminate it.
Adding `-monitor stdio` and issuing `cont` command in there, or
avoiding `-S` option, makes the guest boot, and while it does that,
it shows seabios messages for sure. This happens with all combinations
f video backend (gtk, sdl, spice) and guest video device (stdvga,
virtio-vga, qxl) which I tried.
I don't know what to do with this bug report. The behavior you
observe is not what I see. But my testing is done on a bookworm
system, - maybe there's a bug in some other component in sid, -
I'll try running it there, but no promises since I don't want to
replace my main system with sid.
But at the very least, please confirm: the guest screen is completely
blank, there's no text/message displayed on it at all, right?
Thanks,
/mjt
