For a Power-Safe (fs-qnx6.so) filesystem, the secondary boot loader validates the filesystem and locates the most recent stable snapshot. It then presents all appropriate files from the .boot directory as a scrolling list, from which you can select the required boot image.
If the .boot directory contains only a single applicable file, it's booted immediately; otherwise, the loader pauses for 3–4 seconds for a key press. You can use the up and down arrows to move from one file to another, and press Enter to select it. You can also press Home and End go to the extremes of the list. At most 10 files are displayed on the screen; to see more files, keep pressing the up or down arrows to make the list scroll.
If you don't press a key, then after the timeout, the loader boots the default image. This file is always displayed as the first item in the list, and is the file with the most recent modification time (using the larger inode number as a tie-breaker). In general this should be the image recently copied into the directory; you can use the touch utility to change the default. To determine the default, type:
ls -t /.boot | head -1
You can update the boot loader to a newer version without reformatting (or losing the the filesystem contents), by using mkqnx6fs -B.
You can boot only little-endian filesystems (i.e., those formatted with mkqnx6fs -el on any machine, or natively formatted on a little-endian platform with an unspecified endian-ness).
The boot loader supports only two indirect levels of block hierarchy; since with a 512-byte block, the cutover is at 128 KB, it is likely that filesystems formatted with mkqnx6fs -b512 won't be bootable. With a 1 KB block (the default), the cutover is at 1 GB.
The boot loader may display the following error messages: