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C.6. USB 3 / xHCI Support
USB 3 (xHCI) USB host adapter emulation is supported in Red Hat Enterprise Linux 7.2 and above. All USB speeds are available, meaning any generation of USB device can be plugged into a xHCI bus. Additionally, no companion controllers (for USB 1 devices) are required. Note, however, that USB 3 bulk streams are not supported.
Advantages of xHCI:
- Virtualization-compatible hardware design, meaning xHCI emulation requires less CPU resources than previous versions due to reduced polling overhead.
- USB passthrough of USB 3 devices is available.
Limitations of xHCI:
- Not supported for Red Hat Enterprise Linux 5 guests.
See Figure 16.19, “Domain XML example for USB3/xHCI devices” for a domain XML device example for xHCI devices.