During boot, linux would sometimes overwrites control of a powered off
slot before powering it on. Unfortunately QEMU interprets that as a
power off request and ejects the device.
For example:
/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -S -machine q35 \
-device pcie-root-port,id=pcie_root_port_0,slot=2,chassis=2,addr=0x2,bus=pcie.0 \
-monitor stdio disk.qcow2
(qemu)device_add virtio-balloon-pci,id=balloon,bus=pcie_root_port_0
(qemu)cont
Balloon is deleted during guest boot.
To fix, save control beforehand and check that power
or led state actually change before ejecting.
Note: this is more a hack than a solution, ideally we'd
find a better way to detect ejects, or move away
from ejects completely and instead monitor whether
it's safe to delete device due to e.g. its power state.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Tested-by: Igor Mammedov <imammedo@redhat.com>
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