usbd.irx

usbd.irx is a driver file for the PlayStation 2 (PS2) that enables USB mass storage device support, specifically for accessing files on a USB drive. It works in conjunction with the usbhdfsd.irx driver and is often used with homebrew applications like Open PS2 Loader (OPL) to load games from USB drives.

https://github.com/xerpi/PS2InfoGB_rev6c_dsmod/blob/master/ps2/irx/usbd.irx