Understanding the BOOTWIZ.OSS File
Contents

Introduction

File Format

The <disks> Section

The <partitions> Section

The <oses> Section

Introduction

This guide has been created to give you a better understanding of the BOOTWIZ.OSS file. When working with this file (adding an OS menu entry manually, for example), it's necessary to know how to read it. Entering incorrect information can cause OSS to reset the file or render an OS unbootable through OSS.

If you have OSS installed on your computer and need help finding the BOOTWIZ.OSS file, please click here.
File Format

The BOOTWIZ.OSS file is a standard XML file. The most common encoding format is UTF-8, though ANSI is sometimes used.

Due to the sensitive nature of this file, it's strongly recommended that you only use a standard text editor to make changes to the file. I've found the Windows Notepad program to work very well for this.

A copy of the file being examined in this guide can be downloaded. It may help to have it open in Notepad as you read the guide.

Download
Sample BOOTWIZ.OSS file -- Right-click on the link and select Save Target As... from the pop-up menu to save a copy to your computer.

This is what the contents of the file look like. Depending on the number of drives, partitions and operating systems installed, yours may contain a lot more information.

<?xml version="1.0" encoding="UTF-8" ?>
<bootwiz>
    <disks>
        <id633667013 bios_num="128" crc="120032723" real_bios_num="128" serial="35325" size="134215679" />
        <id3440059480 bios_num="129" crc="136308743" real_bios_num="129" serial="1109" size="136312799" />
    </disks>
    <cds />
    <partitions>
        <id1709083925 begin="63" crc="36865" disk="633667013" fs="ntfs" number="1" serial="2b645f8c7e5f8c8a" size="67210720" type="7" />
        <id2137937787 begin="67211264" crc="22225" disk="633667013" fs="fat32" number="2" serial="413e7c40" size="204800" type="12" />
        <id2457113254 begin="67416064" crc="36865" disk="633667013" fs="ntfs" number="3" serial="773e9a5c879a5cfa" size="52428800" type="7" />
        <id286857235 begin="2048" crc="36865" disk="3440059480" fs="ntfs" number="1" serial="3fca2cb8f92cb8e6" size="136306688" type="7" />
    </partitions>
    <oses>
        <id3056036235 boot_as_ms71="0" boot_as_os2="0" boot_cd_entry="0" boot_partition="1709083925" bootname="bootsect.sys" icon="icon_sys_vista" language="english" lba="1" name_template="%n%l %l(%ll%l)" nthide="0" os_type="ntvista" system_root_identifier="0000000000000000000000000000000006000000000000004800000000000000007e000000000000000000000000000000000000010000004cf9307400000000000000000000000000000000000000000000000000000000\Windows" uninstall_info="1" use_manual_disks_order="0" write_boot="1">
            <partitions>
                <id1709083925 active="1" />
            </partitions>
        </id3056036235>
    </oses>
    <checkfiles />
    <bootmgr default_os="3056036235" disks_order_feature="1" />
</bootwiz>

This sample file shows a computer with two hard drives, four partitions and one operating system (Vista).

A more normal file will usually have an OS entry for a floppy drive (if it exists) and bootable CD entries.

The main sections of interest are the <disks> , <partitions> and <oses> sections. These contain the data needed to boot into an OS.

The <disks> Section

Each drive is assigned a unique ID value by OSS when it is installed or when it rescans the computer and detects new/changed drives. The ID value is located at the beginning of each drive entry:

<disks>
    <id633667013 bios_num="128" crc="120032723" real_bios_num="128" serial="35325" size="134215679" />
    <id3440059480 bios_num="129" crc="136308743" real_bios_num="129" serial="1109" size="136312799" />
</disks>

The real_bios_num value starts at 128 (the booting drive) and increments for each additional drive. Note that the drives are not always listed in order.

The size value is the number of 512 byte sectors that exist on the drive. The size in GB can be calculated using the following formula (where n=size): (((n*512)/1024)/1024)/1024

The <partitions> Section

All detected partitions are listed in this section. In this sample file, there are four. As with the drives, each has a unique ID value assigned to it:

<partitions>
    <id1709083925 begin="63" crc="36865" disk="633667013" fs="ntfs" number="1" serial="2b645f8c7e5f8c8a" size="67210720" type="7" />
    <id2137937787 begin="67211264" crc="22225" disk="633667013" fs="fat32" number="2" serial="413e7c40" size="204800" type="12" />
    <id2457113254 begin="67416064" crc="36865" disk="633667013" fs="ntfs" number="3" serial="773e9a5c879a5cfa" size="52428800" type="7" />
    <id286857235 begin="2048" crc="36865" disk="3440059480" fs="ntfs" number="1" serial="3fca2cb8f92cb8e6" size="136306688" type="7" />
</partitions>

Important values for partitions are listed below:

begin = Starting sector of the partition.

disk = ID of drive on which the partition exists.

fs = File system (format) of partition.

number = Partition table slot number for Primary partitions (1 through 4), or 5 or higher for Logical partitions.

size = Number of 512 byte sectors in the partition. Size in GB can be calculated using the following formula (where n=size): (((n*512)/1024)/1024)/1024

type = Partition type. I won't list them all here, but 7=NTFS and 12 = FAT32.

IMPORTANT: The partitions of very often not listed in order. Always use the ID value of the drive (disk ID), partition type and size to make sure you're selecting the correct partition ID value to use in a manually added OS entry.

For example: If I'm looking for the third Primary partition (2nd NTFS partition) on the booting hard drive, the partition ID value would be: 2457113254

Using a screenshot of what Disk Director shows (in Manual Mode) can be very helpful to ensure you're getting the correct ID value.

1
The <oses> Section

This section contains all of the OS menu entries, floppy entry and bootable CD entries. Each entry will have a unique ID value. In this sample file, only a Vista entry has been detected and it has the ID value of 3056036235.

<oses>
    <id3056036235 boot_as_ms71="0" boot_as_os2="0" boot_cd_entry="0" boot_partition="1709083925" bootname="bootsect.sys" icon="icon_sys_vista" language="english" lba="1" name_template="%n%l %l(%ll%l)" nthide="0" os_type="ntvista" system_root_identifier="0000000000000000000000000000000006000000000000004800000000000000007e000000000000000000000000000000000000010000004cf9307400000000000000000000000000000000000000000000000000000000\Windows" uninstall_info="1" use_manual_disks_order="0" write_boot="1">
        <partitions>
            <id1709083925 active="1" />
        </partitions>
    </id3056036235>
</oses>

Important values for OS entries are listed below:

boot_partition = The partition ID value of the booting partition for this entry. In the case of a Windows OS, this is the partition that would the Active.

icon = Icon used for the entry. Normal values are icon_sys_vista (Vista), icon_sys_win (XP), icon_sys_linux (Linux).

name_template = Name shown in the OSS menu for this entry. If set by OSS, it will often be coded and look like this: %n%l %l(%ll%l). It can be changed to whatever text you want for that entry.

os_type = The OS type for the entry. Normal values are ntvista (Vista), ntxp (XP), linux (Linux).

system_root_identifier = Vista only. Won't exist in manually added entries.

multi = Pre-Vista (boot.ini Windows, like XP) only. May or may not exist in manually added entries.

use_manual_disks_order = If set to 1, this enables the Disk Order feature. This option should not be used with Vista or Windows 7 entries.

write_boot = If 1, the boot sector for the booting partition of this entry will be written when OSS boots it. Normally, this is fine for any automatically detected OS entries and is the default. However, when you manually added an entry, the saved boot sector file won't exist and this option should be disabled (set to 0).

Most of these settings can be changed using the OSS program. However, there are cases where settings gets incorrectly applied or must be added/changed manually. In those cases, editing the file is required.

Each OS entry also has a <partitions> section. This section is where the Active and hidden partitions are set. Note that these settings apply only to the OS entry in which they reside.

In this sample file, the Vista entry has the Vista partition (which is also the booting partition) set Active:

<partitions>
    <id1709083925 active="1" />
</partitions>

If I want to hide the Temp partition, it would look like this:

<partitions>
    <id1709083925 active="1" />
    <id2457113254 hidden="1" />
</partitions>
It is not necessary to enter any partitions in this section that would be set to a zero value. The default for each partition is 0 (not Active and not hidden).
There should only be one partition per drive set as Active. Also, under normal circumstances, a booting partition should not be set as both Active and hidden.
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