Loading a RAM disk at boot time

The feature to load a RAM disk from a diskette at boot time has existed almost from the beginning (it existed in 1992). Since then, some features have been added or modified. It is possible to load a RAM disk image from the boot diskette at a specific offset and to load it from a different diskette.

There are two ways to specify the RAM disk parameters.

• Use the rdev command to set the boot parameters. See section 3.2 for details.
• Set the ramdisk_start, load_ramdisk and prompt_ramdisk parameters from the kernel command line. This is how to do it in LILO:

  root=/dev/fd0
  append ramdisk_start=0 load_ramdisk=1 prompt_ramdisk=1
  

It is possible to put a file system on the first part of the diskette (and install LILO there) and to use the rest of the diskette for the compressed RAM disk image. Use a size argument to the mkfs command to specify the number of blocks for the file system.

It is also possible to put a (non-compressed) file system on the boot diskette and load the entire boot diskette as a RAM disk at boot time. Even the kernel, the LILO second stage boot loader and the map file would be loaded into the RAM disk. Advantage is that the same diskette can be used with or without a RAM disk.