make usb boot image

I want to make a usb boot image by the x86-bios(BSP)that is downloaded from
I have formated the USB flash disk, like this:

  1. fdisk /dev/hd10 delete -a
  2. fdisk /dev/hd10 add -b -t 179
  3. mount - e /dev/hd10
  4. mkqnx6fs /dev/hd10t179

I copy the x86_apic.ifs to the usb flash disk(under /.boot directory), then i boot a x86PC by the usb flash disk after i set the pc booting from usb.
But the PC always dispay “boot from usb device QNX 1.2b boot loader”, and stop.
please help me , thank you very much!