USB bus standard

When redirecting USB peripherals based on QEMU, we often encounter all kinds of USB problems. This paper gives a brief introduction to the USB bus type and speed standard.

1.USB bus type:

OHCI (Open Host Controller Interface) is a standard that supports USB1.1, but it is not just for USB

UHCI (Universal Host Controller Interface), which is dominated by Intel, is the interface standard for USB1.0, 1.1, and is incompatible with OHCI.

EHCI (Enhanced Host Controller Interface) is the interface standard of USB2.0 dominated by Intel.

XHCI (eXtensible Host Controller Interface), which is the interface standard of USB3.0, has a great improvement over the previous three in speed, energy saving, virtualization and so on.

2.USB-SPEED:

LOW:usb1.0 (usb low speed device)

FULL: usb1.1 (usb full speed device)

HIGH:usb2.0 (usb high-speed equipment)

SUPER:usb3.0 (usb Ultra High Speed equipment)