Public bug reported:
When using indpendent transport and backend in this case virtio-net-
device transport, none of the acceleration features are set after guest
probes the transport the backend is plugged into. For virtio-net this
leads to low throughput/performance. This holds true for virtio-mmio,
PCI transports and most likely for others as well (CCW, S390) and other
backends
Command to run:
./qemu-system-arm -enable-kvm -smp 2 -kernel zImage -dtb ./guest-a15.dtb -m 512
-M vexpress-a15 -cpu cortex-a15 -nographic \
-append "root=/dev/vda rw console=ttyAMA0 rootwait" -drive
if=none,file=/mnt/gauss.root,id=vm1 \
-device virtio-blk-device,drive=vm1 -netdev type=tap,id=net0,ifname=tap0 \
-device virtio-net-device,netdev=net0,mac="52:54:00:12:34:58"
For x86 same virtio command for network.
** Affects: qemu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1286253
Title:
virtio-net acceleration features not set when plugged into backend
dynamically
Status in QEMU:
New
Bug description:
When using indpendent transport and backend in this case virtio-net-
device transport, none of the acceleration features are set after
guest probes the transport the backend is plugged into. For virtio-net
this leads to low throughput/performance. This holds true for
virtio-mmio, PCI transports and most likely for others as well (CCW,
S390) and other backends
Command to run:
./qemu-system-arm -enable-kvm -smp 2 -kernel zImage -dtb ./guest-a15.dtb -m
512 -M vexpress-a15 -cpu cortex-a15 -nographic \
-append "root=/dev/vda rw console=ttyAMA0 rootwait" -drive
if=none,file=/mnt/gauss.root,id=vm1 \
-device virtio-blk-device,drive=vm1 -netdev
type=tap,id=net0,ifname=tap0 \
-device virtio-net-device,netdev=net0,mac="52:54:00:12:34:58"
For x86 same virtio command for network.
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