Bootable Installable File System and Remote Initial Program Load Method
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Rasmussen, EC: AUTHOR [+3]
This article describes a method for booting a personal computer (PC) operating system (OS) from an installable file system (IFS) or from a remote (network attached) file system.
Bootable Installable File System and Remote Initial
describes a method for booting a personal
computer (PC) operating system (OS) from an installable file system
(IFS) or from a remote (network attached) file system.
provides the ability to install and use new, possibly
vendor written file systems. However, OS/2 needs to read in a number
of files prior to IFS installation. The bootable IFS (BIFS)
mechanism described herein allows these files to be loaded from a
partition or device managed by an IFS. Without this mechanism these
files would need to reside on a disk managed by a file allocation
table (FAT) file system, which is built into the OS/2 kernel.
mechanism allows installed file systems (file system
drivers or FSDs) to be built as separate modules. The FSDs are loaded
during the initialization of OS/2. An FSD must provide a set of file
I/O functions to be called by the OS/2 kernel. The OS/2 kernel
provides a set of helper functions for use by the FSDs. An FSD may
provide its own device driver and may store files in any manner it
chooses. This is particularly valuable for the support of remote file
systems, where the files reside on a host machine or a network
IFS mechanism is an extension of the IFS
mechanism. OS/2 initialization is modified to load the files it
needs prior to FSD loading via a miniature IFS (mini-FSD). By
providing a mini-FSD and the "black box" code defined below, a file
system author can allow OS/2 to initialize without using the FAT file
with a bootable IFS installed does not need a
partition or device managed by the FAT file system to contain the
system files. In the case of a remote FSD, the OS/2 machine does not
need to contain any disk drives.
1. The Black Box receives control from the PC
hardware/firmware at power-on or re-boot.
2. The Black Box loads three files into memory and passes
control to OS2LDR.
3. OS2LDR performs its initialization and passes control to
4. OS2KRNL does relocation fix-ups on the mini-FSD and
5. OS2KRNL begins initialization, using the mini-FSD stage
one interfaces until the disk device driver is loaded.
6. OS2KRNL proceeds with initialization using the mini-FSD
stage two interfaces.
7. OS2KRNL loads the FSD (and associated device driver if
8. The mini-FSD passes whatever information is necessary to
the FSD and terminates.
9. OS/2 continues, using the FSD.
FILE SYSTEM COMPONENTS
1. BLACK BOX
The Black Box must take control at system start-up. The
most common ways to do this are to put its initial code in the first
sector of the disk in drive A: or drive C:, or to use code in
an adapter to trap interrupt 19....