What were you trying to do that didn't work?

Chains in packed vq must be tracked by the last descriptor id, but QEMU is currently tracking them by the first one. This causes the driver cannot communicate with the device anymore.

Please provide the package NVR for which bug is seen:

How reproducible:

Always

Steps to reproduce

Create a virtio-net-pci device with VIRTIO_NET_F_MRG_RXBUF feature but not the VIRTIO_RING_F_INDIRECT_DESC feature. Try to send big packets.

Expected results

Packets are tx and rx

Actual results

Packets are not tx nor rx

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Avail: https://lists.nongnu.org/archive/html/qemu-devel/2024-05/msg01510.html

Used: https://lists.nongnu.org/archive/html/qemu-devel/2024-04/msg01025.html (already in QEMU 9.0)