Recovery cmd.exe in Litetouch WinPE October 29, 2009

(New for MDT 2010)

One of the things we worked on for MDT 2010 were improvements to the user interface for “New Computer” scenarios in the Windows Pre-installation Environment (WinPE).

WinPE is used by MDT 2010 Litetouch, and SCCM to prepare the machine for OS installation. It’s a bare bones implementation of Windows, with out the Windows Shell (Start Button), and typically only runs with a command prompt “console” window.

One of the distracting things about BDD 2007 and MDT 2008, was the Console window that appeared at the start of the WinPE Litetouch New Computer” process. It really didn’t do anything, was a little distracting, and didn’t give MDT the feel of a polished product.

It’s fairly easy to use a different shell for WinPE, however we were concerned about proper error recovery. If something goes wrong with any child script in the process, we want to ensure that we have a chance to debug the problem before the machine reboots. If we replaced the standard WinPE shell with something that didn’t properly handle errors, then WinPE could reboot before we knew what happened.

We also wanted the ability to break out into a cmd.exe prompt if we needed to debug a background process or verify something else.

The final solution was to make some modifications to BDDRun.exe to act as a wrapper around wpeinit.exe. It does two things:

• It calls wpeinit.exe, and if wpeinit.exe returns any failure, it will launch a cmd.exe prompt allowing debugging.
• It also launches a thread in the background monitoring for the user to press the F8 button, if pressed, it will launch a cmd.exe window for debugging.
• If there are any instances of cmd.exe (spawned by pressing F8), and wpeinit.exe exits ready for a reboot, the bddrun.exe program will wait until all cmd.exe windows are closed. So be sure to close all windows if you expect the process to continue.
• If you wish to disable the F8 feature, modify the unattend_pe_x86.xml and unattend_pe_x64.xml in the templates directory of your MDT 2010 installation, and replace “/Bootstrap” with “/BootstrapNoSF8”.

Not sure why someone would want to disable the F8 windows (perhaps the F8 keystroke conflicts with another application. Disabling F8 won’t make things secure. Someone could still come in with a WinPE DVD and bypass the security.

Why is it called “SF8″ not “F8″? I had originally programmed the keystroke to be Shift-F8 (similar to the Shift-F10 used by Windows Setup. However the feedback I got from early builds is that it should mimmic SCCM behaviour which uses just F8. I changed the keystroke from F8 to Shift-F8, but forgot to change the command line string from /BootstrapNoSF8 to /BootstrapNoF8. Sorry about that…

Keith