tboot" -- Technical Information" "

Describe the tertiary bootstrap
Booting is the process of loading COHERENT into memory and setting it into motion. This normally occurs after you have turned on your computer. The term comes from the old expression about pulling one's self up by one's bootstraps.

Booting can be quite involved, and uses a number of files, depending upon the version of COHERENT being booted and the medium from which you are booting it. The subject of this article, tboot, is the booting program that performs tertiary booting.

To grasp what is meant by ``tertiary booting'', consider how the boot sequence works:

1.
The BIOS loads the first 512 bytes off of the first hard disk and runs it. This program is called the mmaasstteerr bboooott. Mark Williams Company recommends that you use the COHERENT master boot, because it lets you boot off any partition on either of the first two drives.

2.
The master boot loads the first 512 bytes off the active partition and runs that. This program is the ``secondary boot'' program. The secondary boot is generally responsible for loading the operating system off the active parition and running it.

Recent releases of COHERENT need a more sophisticated program to load the operating system than can fit into 512 bytes. In these releases of COHERENT, the secondary boot loads a program off the root file system; this program is called the ``tertiary boot'', or tboot.

tboot evaluates the hardware of your computer to provide the operating system (COHERENT) with vital information. This evaluation allows COHERENT to run without modification on a wider range of hardware.

tboot is responsible for loading the operating system kernel. It first looks for a file called autoboot, which it then loads. If autoboot does not exist, tboot prompts you to type in the name of a kernel, e.g., begin (during installation) or coherent. If you do not remember the name of the kernel you wish to boot, you can type dir or ls for a list of files in your root file system.

Pressing the spacebar when the prompt is displayed prevents execution of /autoboot and causes tboot to pause. You can then type the name of an alternate kernel to load (assuming it already resides within the root directory), type ls to see a listing of files, or type info for a display of hard-drive parameters.

See Also