installboot copies the bootblock to a bootable partition. The bootstrap is written into the bootblock area on the partition, right in front of the superblock, and hence limited in size to 8192 bytes.
The bootstrap resides in the first few blocks on the partition (as specified by Commodore-Amiga Inc.) The bootstrap is loaded into memory by the ROM from bootable devices: RDB devices, where the partition is marked as bootable, or (not on the DraCo) floppy disks in Amiga format (880K/1760k).
In the presence of more than one bootable partition/floppy disk, the partition is chosen by the bootpriority (from the RDB), which can be overridden by the operator from the boot menu (on Amiga machines, hold down the outer mouse buttons during boot; on DraCo machines, press the left mouse button when prompted).
On RDB devices, the whole bootblock is loaded by the ROM. The number of boot blocks in the RDB partition entry must be correct.
On floppy disks, the ROM always loads the first two blocks (1024 bytes), and the bootblock allocates memory and loads the whole bootblock on startup.
After receiving control, the bootblock uses the stand-alone filesystem code in “libsa.a” to load the kernel from the filesystem on the partition it was started from. The code for the boot program can be found in
/usr/mdec/bootxx_fd (floppy disk code) or
/usr/mdec/bootxx_ffs (generic RDB disk code).
The arguments are:
-l newcommandline
Specify a different command line to replace the default.
bootblock
The file containing the bootblock (normally /usr/mdec/bootxx_ffs for RDB devices).
device
The name of the character special device specifying the partition on which the bootstrap is to be installed.