How to develop a USB mass storage driver?

:blush: I have a USB disk. Its protocol is 0x50(Bulk Only) and its subclass is 0X06(SCSI). How to develop a USB disk driver on QNX 6.2.0. cam-disk.so, io_blk.so, fs-dos.so maybe useful to make the work easy, but how to use these dll.

You really cannot. The block subsystem is not documented.