Bootable CD-ROM Design Considerations

Use the El Torito CD Support component to create a bootable CD-ROM from which you can boot and run your target system. The El Torito CD Support component adds the components required to create a bootable CD-ROM. For more information, see El Torito CD Support in Windows XP Embedded Studio Help.

Creating a bootable CD-ROM also requires the Enhanced Write Filter (EWF) component. This component provides the ability for a read-only CD-ROM drive to appear as a writeable file system. Disk-write operations that would typically update the disk media contents are instead stored in physical system memory (RAM). For more information, see Enhanced Write Filter.

To create a bootable CD-ROM that includes the El Torito CD component, your target system must meet the following requirements.

Hard disk requirements

Use the Windows XP Logical Disk Manager or Diskpart to create and adjust these hard disk settings. For more information on using Diskpart, see Configuring a Hard Drive with Diskpart and Windows PE.

Hard Disk requirementDescription
A primary FAT partition as the first partition on the disk. This partition must be bootable and its size must be smaller than that of the target media (typically 650MB for a 74 minute CD-ROM and 700MB for an 80 minute CD-ROM). A partition size of 625MB is recommended. You can use FAT32, FAT16, or NTFS. FAT32 is recommended.FAT32 provides smaller cluster size and is typically used over FAT16 because it can support larger sized disks. NTFS can provide additional security benefits over FAT file systems; however, it may reduce the performance of your run-time image.
If you choose to use the FAT16 file system, you must run the BootPrep utility.

BootPrep is not required if you use FAT32 or NTFS.

BootPrep overwrites the FAT16 boot sector to enable booting Windows XP Embedded.

To use the BootPrep utility:

  1. Create a Windows startup disk and copy the BootPrep utility to it.
  2. Boot to the MS-DOS prompt and type the following command:
    bootprep /dC

For more information, see BootPrep.

At least 8 MB of raw, unallocated space must be available on the disk.This space is used to configure the Enhanced Write Filter (EWF) during the First Boot Agent (FBA) phase and is deleted before the CD image is packaged. For more information, see EWF Performance Considerations
There cannot be more than a total of three existing partitions (or logical drives) on the disk because the EWF Volume that is created is considered a partition. Hard disks are limited to a maximum of four primary partitions.

Note   Multiple El Torito volumes or partitions are not supported; only a single volume can be protected.

The EWF Volume will be configured immediately after the last primary partition, or within an extended partition. The EWF Volume cannot be setup immediately after an extended partition. For more information see EWF Volume Configuration.

Additional Requirements

Additional requirementDescription
The CD-ROM must be configured on the target Integrated Device Electronics (IDE) bus. For example, if the CD-ROM runs on the target as primary master, configure the CD-ROM as primary master on the IDE bus. FBA configures the CD-ROM location during system setup. If the location of the CD-ROM changes after FBA, you receive a message that new hardware was detected. This is because the CD-ROM was found at a different location than when FBA and Plug and Play enumeration occurred.
A CD-ROM authoring package that enables you to create a CD-ROM from an ISO image file.The Hd2iso.exe tool creates an ISO-9660 image (.iso) from your run-time image.
A BIOS that supports booting from CD-ROMThe BIOS must be able to boot from an IDE CD-ROM device. For more information about updating your system BIOS, refer to your hardware manufacturer's documentation.

See Also

Disabling Disk Defragmentation | Building a Bootable CD-ROM Run-Time Image | How to Create a Bootable CD-ROM | Enhanced Write Filter | Bootable CD-ROM

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