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Description of problem: Can't find usb-hub device in guest under EHCI adapter Version-Release number of selected component (if applicable): qemu-kvm-0.12.1.2-2.175.el6.x86_64 How reproducible: 100% Steps to Reproduce: 1.Boot guest with usb-hub and -device usb-ehci,id=ehci and usb-storage #/usr/libexec/qemu-kvm -M rhel6.2.0 -enable-kvm -m 2G -smp 2,cores=2,threads=1,sockets=1 -name RHEL6.1_32 -uuid 50eba0fa-c3bc-4634-9c87-e46fc4dafab9 -rtc base=utc,clock=host,driftfix=slew -boot menu=on -drive file=/root/zhangjunyi/RHEL6.1_64-copy-2.qcow2,if=none,id=drive-ide-0-0,media=disk,format=qcow2,cache=none,werror=stop,index=0 -device virtio-blk-pci,drive=drive-ide-0-0,id=ide0-0-0,bootindex=1 -netdev tap,id=hostnet1 -device virtio-net-pci,netdev=hostnet1,id=net1,mac=78:2B:CB:AF:11:11 -vnc :10 -monitor stdio -balloon none / -device usb-ehci,id=ehci -device usb-hub,bus=ehci.0,port=1 -device usb-hub,bus=ehci.0,port=2 -device usb-hub,bus=ehci.0,port=3 -device usb-hub,bus=ehci.0,port=4 / -device usb-storage,bus=ehci.0,port=1.1,drive=usbstick1 -drive if=none,id=usbstick1,file=/root/zhangjunyi/usbdevice1.qcow2 2.check usb in qemu #(qemu) info usb Device 0.1, Port 1, Speed 12 Mb/s, Product QEMU USB Hub Device 0.2, Port 2, Speed 12 Mb/s, Product QEMU USB Hub Device 0.3, Port 3, Speed 12 Mb/s, Product QEMU USB Hub Device 0.4, Port 4, Speed 12 Mb/s, Product QEMU USB Hub Device 0.5, Port 1.1, Speed 12 Mb/s, Product QEMU USB MSD 3.in guest Actual results: After step3,can't find usb-hub device and usb-storage and saw wrong message "hub 1-0:1.0: Cannot enable port 1. Maybe the USB cable is bad?" Expected results: 1.if we support usb-hub work under EHCI adapter usb-hub works well and find usb-storage device 2.if we don't support usb-hub&EHCI adapter should not let guest boot and promote friendly message. Additional info: Usb-hub works well under UHCI adapter #-usb -device usb-hub,bus=usb.0,port=1 -device usb-hub,bus=usb.0,port=2 -device usb-storage,bus=usb.0,port=1.1,drive=usbstick1 -drive if=none,id=usbstick1,file=/root/zhangjunyi/usbdevice1.qcow2
The USB Hub emulated by qemu is a USB 1.1 Hub and thus doesn't work on EHCI by design. You can hook it up nevertheless by using a companion controller setup (see bug 728120 for how to do that). Adding USB 2.0 support to the hub is possible. It is a non-trivial effort though and involves a bunch of changes in both usb-ehci and usb-hub to implement split-transfers. Very unlikely to happen for RHEL-6, you might want to file a RFE bug for RHEL-7 though.