u32 flag 

DEVICE flags:

(1<<0)   (1)      dev_hdd0 
(1<<1)   (2)      dev_usb000
(1<<2)   (4)      dev_usb001
(1<<3)   (8)      dev_usb002
(1<<4)   (16)     dev_usb003
(1<<5)   (32)     dev_usb004
(1<<6)   (64)     dev_usb005
(1<<7)   (128)    dev_usb006
(1<<8)   (256)    dev_usb007
(1<<11)  (2048)   dev_bdvd
(1<<15)  (32768)  NTFS/EXTx ISO

OR flags:

(1<<32) homelaunch / launch homebrew/psn from USB

(1<<24) PS3 ISO

(1<<24) | (1<<23) PS2 ISO

(1<<23) PSX ISO