wimboot is a boot loader for Windows Imaging Format (.wim) files. It enables you to boot into a Windows PE (WinPE) deployment or recovery environment.

You can use wimboot with iPXE to boot Windows PE via HTTP. With a Gigabit Ethernet network, a typical WinPE image should download in just a few seconds.


A light bulb


wimboot can download images at the full speed supported by your network, since it can use HTTP rather than TFTP.


wimboot allows Windows to reuse the memory that was used to hold the RAM disk image; there is no wasted memory.

Ease of use

wimboot works directly with .wim image files; there is no need to wrap your .wim into an ISO or FAT filesystem image.

BIOS/UEFI compatibility

wimboot allows you to use a single configuration and set of files to boot under both BIOS and UEFI environments.


You can download the latest version of the wimboot binary from https://github.com/ipxe/wimboot/releases/latest/download/wimboot. This is a hybrid binary that will work on both BIOS and 64-bit UEFI systems (including UEFI systems with Secure Boot enabled).

You can also download alternative binaries (e.g. for 32-bit UEFI systems) from https://github.com/ipxe/wimboot/releases/latest.

Older versions are available from https://github.com/ipxe/wimboot/releases.

The source code is maintained in a git repository at https://github.com/ipxe/wimboot.

Getting started

If you have a Windows installation DVD-ROM (Vista, Server 2008, or more recent), and a web server (such as Apache or IIS), then you have everything you need to start using wimboot.

Extract the Windows boot files


Copy the contents of the Windows installation DVD-ROM to a directory on your web server (e.g. /var/www/win7 for Apache, or C:\inetpub\wwwroot\win7 for IIS).

If you do not have enough disk space to copy the entire contents of the DVD-ROM, then you may copy only the following files:


Download wimboot

Download the latest version of wimboot and save it to the same directory on your web server.

Create the iPXE script

Create a text file boot.ipxe in the same directory on your web server, containing:

  kernel wimboot
  initrd boot/bcd         BCD
  initrd boot/boot.sdi    boot.sdi
  initrd sources/boot.wim boot.wim


Boot using iPXE from the URL of your iPXE script, e.g. http://my.web.server/win7/boot.ipxe. You should see iPXE download your Windows boot files via HTTP and boot into the Windows installer:

wimboot booting Windows 7

Windows 7 installer booted via wimboot

Next steps

You can use wimboot to boot any bootable .wim image. See the Windows PE tutorial for information on how to create and customise your own .wim images.


wimboot is free, open-source software licensed under the GNU GPL.


Portions of the wimboot development have been sponsored by:

Jump Trading

2Pint Software

Digital Intelligence

Advanced topics

Some books

Multi-image WIM files

A WIM file can contain multiple bootable images. You can use the index=<N> command-line option to select the image to be booted. For example:

  kernel wimboot index=2

Injected files

You can provide additional files to wimboot. These files will appear within the X:\Windows\System32 directory. For example:

  kernel wimboot
  initrd winpeshl.ini     winpeshl.ini
  initrd startup.bat      startup.bat
  initrd boot/bcd         BCD
  initrd boot/boot.sdi    boot.sdi
  initrd sources/boot.wim boot.wim

You can use this to control the boot process after Windows PE has started. For example, you can use a startup batch file to automatically start the Windows installer from a network share.

You can disable this behaviour by using the rawwim command-line option. For example:

  kernel wimboot rawwim

Custom boot manager

wimboot will attempt to extract an appropriate boot manager (such as bootmgr, bootmgr.exe or bootmgfw.efi) from the WIM file.

You can disable this behaviour by explicitly providing an appropriate set of boot manager binaries. For example:

  kernel wimboot
  initrd bootmgr              bootmgr
  initrd efi/boot/bootx64.efi bootx64.efi

Disabling automatic BCD modifications

wimboot will automatically patch standard BIOS-compatible boot configuration data (BCD) files to allow them to be used on UEFI systems, by changing all occurrences of the string “.exe” to “.efi”.

You can disable this behaviour by using the rawbcd command-line option. For example:

  kernel wimboot rawbcd

Disabling debug messages

wimboot will display some debug messages by default, to assist in diagnosing problems that may occur during booting.

You can disable these debug messages by using the quiet command-line option. For example:

  kernel wimboot quiet

Displaying graphical boot messages

wimboot will force the Windows boot manager to display error messages in text mode. It does this to work around a bug in some versions of the Windows boot manager, which would otherwise fail to display error messages unless suitable font files are provided.

You can disable this behaviour by using the gui command-line option and by providing all of the required font files. For example:

  kernel wimboot gui
  initrd boot/fonts/segmono_boot.ttf  segmono_boot.ttf
  initrd boot/fonts/segoe_slboot.ttf  segoe_slboot.ttf
  initrd boot/fonts/segoen_slboot.ttf segoen_slboot.ttf
  initrd boot/fonts/wgl4_boot.ttf     wgl4_boot.ttf

Disabling paging

wimboot will automatically use paging to relocate the data files above 4GB if possible, to allow for the use of large .wim files on BIOS systems.

You can disable this behaviour by using the linear command-line option. For example:

  kernel wimboot linear


For more detailed information about the internal workings of wimboot, see the wimboot architecture guide.


Try adding the commands imgstat and prompt to your iPXE script, to allow you to check that all of the files have loaded correctly. For example:

  kernel wimboot
  initrd boot/bcd         BCD
  initrd boot/boot.sdi    boot.sdi
  initrd sources/boot.wim boot.wim

Check that only the expected files are present in the list. You may need to use the imgfree command to discard any unwanted files.

You can also try adding the pause command-line option for wimboot. For example:

  kernel wimboot pause

This will instruct wimboot to wait for a keypress before booting Windows, to give you a further opportunity to observe any messages that may be displayed.

If you are unable to resolve your problem, then you can contact the iPXE developers and other iPXE users.

wimboot.txt · Last modified: 2021/04/30 11:01 by mcb30
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