Guru Boot Manager

... the smallest boot manager for advanced users ...

Version 2.0

1999-2001, by Andrew Removsky (arem@iname.com)

Overview of GuruBoot
How It Works
Writing Configuration File
How to Run GuruBoot
GuruBoot Configuration File Example
Download GuruBoot

Overview of GuruBoot

The GuruBoot is designed for advanced users who know what Boot Manager is, who want to know what their Boot Manager does and who want to have full control over it.
The GuruBoot allows you:
to have installed several primary operational systems on your PC
to boot from any of the primary system
to hide necessary partitions
to protect booting from any of your primary systems
If you are an advanced user you cannot crash your PC even if it is not booted after incorrect installation of the GuruBoot. Just because you know what "fdisk /mbr" does and you know how to saddle Disk Editor. If not - enjoy yourself without the GuruBoot.

How It Works

Before you use the GuruBoot you have to know how PC boots.

How It Boots

If the boot device is on a hard disk, the BIOS loads the master boot record (MBR) - the first sector on the hard disk. The MBR contains references to four primary partitions with one of which is active. The master boot code in the MBR loads the boot sector of the active partition. Then the boot sector code loads the OS.
Of course you can have more then four volumes. This is done by making one primary partition as Extended. All additional volumes are resided in that Extended partition.

What GuruBoot Does

The GuruBoot stores its code only in the MBR. It recognizes what configuration you want to have by entered password. The configuration consists of the active partition and set of partitions you want to hide on every hard disk.

The Benefit

You know how it works and you control it.

Writing Configuration File

To install the GuruBoot you need to create configuration file.

Boot Entries

Entry contains settings to boot from specified partition.
  entry " text-description " {
      [ password " password-string " ]
      disk disk-number  {
          partition-operation partition-number
          ...
      }
      ...
  }
Parameters

text-description

Specifies text string to output on boot to visualize the entry presence. Usually contains name of OS.
There is an example:
entry " \x1A Windows 2000".
See String Values.

password-string

Specifies unique password to boot from the entry. If the entry does not contain password and empty password value is assumed.
See Password Values.

disk-number

Specifies the number of the hard disk. Bootable disk number is 0.

partition-operation

Specifies how to mark partition on boot:

active Marks the partition as bootable. The entry must contain only one active partition. The active partition is meaningful only for bootable disk 0.

enable Default. Mark the partition as visible.

disable Mark the partition as hidden.

partition-number

Specifies the number of partition to operate on. Valid values are 0, 1, 2 and 3.

Remarks

At least one entry must be specified and up to 8 entries are supported.

Partitions Map

Partitions map specifies what and how partitions are marked as hidden.
  map {
      { original-partition-ID, hidden-partition-ID }
      ...
  }
Parameters

original-partition-ID

Specifies partition ID recognizable by the system. There are examples of partition IDs for some file systems:

0x01 FAT12 file system

0x04 FAT16 file system

0x05 Extended partition

0x06 FAT16 file system

0x07 NTFS or HPFS file system

0x0B FAT32 file system

0x0C FAT32 file system

0x0E FAT16 file system

0x0F Extended partition

hidden-partition-ID

Specifies partition ID not recognizable by the system. When the partition is disabled the GuruBoot changes the original ID to this value.

Remarks

At least one partition map definition must be specified. The value 0 must not be used since means an empty partition. The maximum valid value is 0xFF.

Customizing Output

The set section is used to change default GuruBoot output on boot. This section is optional.
  set {
      [ password_prompt " password-prompt-string " ]
      [ password_wrong " password-wrong-string " ]
      [ password_ok " password-ok-string " ]
      [ disk_error " disk-error-string " ]
      [ no_logo ]
  }
Parameters

password_prompt

Specifies password prompt text. The default is "\nEnter password: ".

password_wrong

Specifies text to output on wrong entered password. The default is "WRONG!\r".

password_ok

Specifies text to output on valid entered password. The default is "OK\r\n\n".

disk_error

Specifies text to output on hard disk I/O error. The default is "Disk IO Error\r\n".

no_logo

Suppresses GuruBoot message on boot.

Tokens

Comments

A comment is text that the GuruBoot compiler ignores. A comment is written in one of the following ways:

The /* (slash, asterisk) characters, followed by any sequence of characters (including new lines), followed by the */ characters.

The // (two slashes) characters, followed by any sequence of characters. A new line terminates this form of comment.

Numerical Values

Numerical values can be specified in decimal, octal or hexadecimal format.
The value is interpreted as decimal if it not begins from 0.
The value is interpreted as hexadecimal if it begins from 0x.
The value is interpreted as octal if it begins from 0.

String Values

A string value is a sequence of characters from the source character set enclosed in double quotation marks (" "). Adjacent strings are concatenated. There is an example:
entry "First entry is " "Windows" {...}
Special characters can be included into strings using escape sequences:

Escape
Sequence
Represents

\a Bell (alert)

\b Backspace

\n New line

\r Carriage return

\" Double quotation mark

\\ Backslash

\xhh ASCII character in hexadecimal notation

Password Values

The GuruBoot recognizes entered password by scan codes. So, if the password string is specified as either "abAB" or "AbaB" both mean the same key sequence.
Functional and control keys can be included into password strings directly as scan codes by embracing in parentheses:
password "a(\x0F)B(\x3B\x1)"
This means the following password key sequence: 'A', 'TAB', 'B', 'F1', 'ESC'
'ENTER' scan code (\x1C) is reserved for submitting the password.

Escape Sequence	Represents
\a	Bell (alert)
\b	Backspace
\n	New line
\r	Carriage return
\"	Double quotation mark
\\	Backslash
\xhh	ASCII character in hexadecimal notation

How to Run GuruBoot

There are two executables of the GuruBoot:

GuruBoot.exe for DOS and Windows 95 family.

GuruBoot32.exe for Windows NT family.

There is a default option:

-h

Show option help.

Building Configuration File

To install the GuruBoot the Configuration File must be created. The GuruBoot can help to make the template by following options:

-b <config_file>

Create the Configuration File using currently installed settings. If the GuruBoot was not installed the same as option -bn.

-bn <config_file>

Create new Configuration File with a map and an entry of current system configuration.

-bs <config_file>
-bns <config_file>

Create the Configuration File with set section.

Installation

The GuruBoot can be installed in two ways.

<config_file>

Install the GuruBoot from the Configuration File.
By default the GuruBoot uses Int 13 Extension to boot from bootable partition resided outside ~8GB.

-x <config_file>

Install the GuruBoot from the Configuration File.
This option disables using Int 13 Extension so the GuruBoot uses CHS (cylinder, head, sector) values to boot. The option is useful for some old BIOSes to install from Windows system since it simulates Int 13 Extension feature. Cannot be used for bootable partitions outside ~8GB.

Uninstallation

The GuruBoot uninstalls itself by overwriting the MBR code. All currently hidden partitions are leaved hidden.

-u

Uninstall the GuruBoot.

Notes

Any program that overwrites the MBR code uninstalls the GuruBoot.
CAUTION:
If you are going to change disk volume structure you must uninstall the GuruBoot first, make what you want and then reinstall the GuruBoot with the Configuration File adapted to the new disk structure (see Building Configuration File).
There is a sample of programs that can change disk structure:

Windows Disk Management/Administrator
,
fdisk
,
PQMagic
,
Partition-It
, etc.

GuruBoot Configuration File Example


  /*
    This is an example of writing GuruBoot Configuration File.
    DO NOT TRY TO INSTALL THIS SAMPLE WITHOUT ADAPTATION.
  */

  map {
    {0x05, 0x15}	// These are my logical volumes
    {0x06, 0x16}	// This is my FAT16 Windows 98 volume
    {0x0B, 0x1B}	// This is my FAT32 Windows 2000 volume
    {0x07, 0x17}	// This is my NTFS Windows 2000 Server volume
  }
  entry "  \x1A Windows 2000" {
    password "Admin"
    disk 0 {
      active  1
    }
  }
  entry "  \x1A Windows 2000 Server" {
    password "(\x01)cape"	// 'ESC', 'A', 'P', 'E'
    disk 0 {
      active	0
      disable	1
      disable	2
    }
    disk 1 {
      enable 	0
    }
    }
  entry "  \x1A Guest Windows \"Press Enter\"" {
    disk 0 {
      disable	0
      disable	1
      enable	3
      active	2
    }
    disk 1 {
      disable	0
    }
    }
  set {
    password_wrong "S.O.S.\a\r"
  }

The screen on PC boot:


 GuruBoot 2.0

    Windows 2000
    Windows 2000 Server
    Guest Windows - "Press Enter"

 Enter password:

Download GuruBoot

GuruBoot 2.0 zip archive, size 52 Kb.

Last Updated: July 21, 2001, by Andrew Removsky (arem@iname.com).

Return Home

Guru Boot Manager

... the smallest boot manager for advanced users ...

Version 2.0

Table of Contents

Overview of GuruBoot

How It Works

How It Boots

What GuruBoot Does

The Benefit

Writing Configuration File

Boot Entries

Parameters

Remarks

Partitions Map

Parameters

Remarks

Customizing Output

Parameters

Tokens

Comments

Numerical Values

String Values

Password Values

How to Run GuruBoot

Building Configuration File

Installation

Uninstallation

Notes

GuruBoot Configuration File Example

Download GuruBoot

active	Marks the partition as bootable. The entry must contain only one active partition. The active partition is meaningful only for bootable disk 0.
enable	Default. Mark the partition as visible.
disable	Mark the partition as hidden.

0x01	FAT12 file system
0x04	FAT16 file system
0x05	Extended partition
0x06	FAT16 file system
0x07	NTFS or HPFS file system
0x0B	FAT32 file system
0x0C	FAT32 file system
0x0E	FAT16 file system
0x0F	Extended partition

GuruBoot.exe	for DOS and Windows 95 family.
GuruBoot32.exe	for Windows NT family.