Is it possible to boot Windows 8 installed to VHD from Windows 7 boot manager?

Question

does anybody have success with booting Windows 8 Dev Preview that is installed to VHD from Windows 7 boot manager?

I have no success with that. However, I have success with booting yet another Windows 7 that installed to VHD from Windows 7 boot manager. After that I just replace VHD file with Win7 to VHD file with Win8. And have an error when trying to boot Win8 VHD with prompt to restart PC. Both VHDs are created using the same method.

I also know that there is another way of dual-boot Windows 7 on hardware PC and Windows 8 on VHD (when boot manager is Windows 8 boot manager). It works well for me.

But topic question is interesting too.

Answer 1

The boot chain is signed and the files are checked during boot strapping. There is no way of an older boot manager to load newer files from the boot chain (this is by design I think).

The security checking could start from BIOS code - MBR is loaded and checked, then PBR(partition boot record) is loaded and checked, then bootmgr (for Vista, Windows 7 and 8) is loaded and checked, then winload.exe is loaded and checked and so on.

Newer boot managers "know" about older boot chains (how to calculate their checksums).

I have not tryed to load Windows 8 (or any other Windows OS) over a so called "boot sector loader". The principle is to create a boot sector loader and give it as "boot sector file" a copy of the PBR of the OS to be loaded. (This way Linux based OS's can be loaded from Windows boot manager).

With a GUI based Windows BCD tool (handling also MBRs and PBRs) like Visual BCD Editor it is simple to do experiments as the complete BCD is displayed and every entity is editable. Moreover Windows loaders are created either individually with one click (and amended for drive and path) or several Windows loaders can be created on one go automatically.

Answer 2

I don't think you can boot Windows 8 from the Windows 7 boot manager. You generally cannot boot a newer version of Windows from an old version of the boot manager. But you should be able to boot Windows 8 off of a VHD with the Windows 8 boot manager.

If you want to boot Windows 8 from a VHD you need to install Windows 8 on the machine with Windows 7, but during the install mount the VHD and then select it for the install. The Windows 8 install won't move the boot manager from the hard drive to the VHD, it will just update the Windows 7 boot manager to the Windows 8 version. This should allow you too boot with the Windows 8 boot manager and the select whether to boot Windows 7 off of the real drive or Windows 8 off of the VHD.

Guide to doing the install.