How to boot an WIM image?

Is it possible to boot from a Windows WIM image or is that not possible? What's the difference between ISO and WIM?

1 Answer

WIM is a multi “image” file format that supports having one of those images declared as “bootable” i.e the typical case of booting a PE environment (boot.wim) contained on MS Windows Install Distributions.

The wim booting process would be something like:

1. The “boot sector" from a particular media is loaded. (MBR on HDD, el Torito on CD/DVD, bootstrap loader on PXE)
2. The "boot sector" passes control to "Bootmgr.exe”
3. "Bootmgr" extracts basic boot information from the "BCD" (Boot Configuration Data)
4. "Bootmgr" opens the WIM
5. "Bootmgr" passes control to "Winload.exe" contained in bootable image of i.e. Boot.wim

ISO and WIM are just different storage file formats with different goals. While the first one is related to the CD/DVD format, the second one is able to hold several images of MS OSs as “snapshots”; I mean as working images of different OSs.