There are a number of boot options that can be used in Vista and Windows Server 2008 that can be a pain to modify (or not possible if you are in a bugcheck loop), that can be done on the fly at boot time. These options are invaluable for diagnosing some problems you may experience on the system, and modifying them in the OS may involve figuring out the bcdedit syntax, the right BCD store to modify, or rebuilding and burning a new install DVD (if the problem is happening during install from media).

Some example boot switches you might want to use are:

  • Adding a debug switch for any type of transport (not just the default serial option that you get in the F8 menu)
  • Opting in or out of no exececute (NX)
  • Capping the amount of system memory (with maxmem or burnmem)
  • Limiting the number of processors (with numproc)

To modify the boot options on a Vista and Windows Server 2008 system, whether it is booting from the hard drive or DVD, you can do the following:

  1. Hit the space bar repeatedly after the BIOS screen goes away.
  2. On the next screen will be the Windows Boot Manager menu where you select the boot operating system.
  3. On this screen hit the F10 button.
  4. This will take you to the Edit Boot Parameters screen where you can edit the boot options in the same way you did with the boot.ini file in previous versions of Windows.
  5. Here you can change the default values to the one-time values you want for this boot.

An example of this is to do a debug using 1394. To do this you change the default values to:

[ /NOEXECUTE=OPTIN /DEBUGPORT=1394 /CHANNEL=40 ]

And you will boot with the debugger enabled on the 1394 bus and with a channel number of 40.

Further switches and examples to come in further posts...