How to determine if WinPE (4) booted from UEFI or BIOS?

Question

I'm looking for a reliable detection method when I boot into WinPE 4 (powershell) (or WinPE 3 (vbs) as an alternative), did I boot from UEFI or BIOS System? (without starting a third-party exe, as I am in a limited environment)

This significantly changes the way you partition Windows deployments as you change and format partition layouts. (GPT vs MBR, etc.)

I have one job that is an adaptation of this C ++ code in powershell v3, but it looks pretty hack:

## Check if we can get a dummy flag from the UEFI via the Kernel ## [Bool] check the result of the kernel fetch of the dummy GUID from UEFI ## The only way I found to do it was using the C++ compiler in powershell Function Compile-UEFIDectectionClass{ $win32UEFICode= @' using System; using System.Runtime.InteropServices; public class UEFI { [DllImport("kernel32.dll")] public static extern UInt32 GetFirmwareEnvironmentVariableA([MarshalAs(UnmanagedType.LPWStr)] string lpName, [MarshalAs(UnmanagedType.LPWStr)] string lpGuid, IntPtr pBuffer, UInt32 nSize); public static UInt32 Detect() { return GetFirmwareEnvironmentVariableA("", "{00000000-0000-0000-0000-000000000000}", IntPtr.Zero, 0); } } '@ Add-Type $win32UEFICode } ## A Function added just to check if the assembly for ## UEFI is loaded as is the name of the class above in C++. Function Check-IsUEFIClassLoaded{ return ([System.AppDomain]::CurrentDomain.GetAssemblies() | % { $_.GetTypes()} | ? {$_.FullName -eq "UEFI"}).Count } ## Just incase someone was to call my code without running the Compiled code run first If (!(Check-IsUEFIClassLoaded)){ Compile-UEFIDectectionClass } ## The meat of the checking. ## Returns 0 or 1 ([BOOL] if UEFI or not) Function Get-UEFI{ return [UEFI]::Detect() } 

It looks pretty simple to get a simple flag.

Does anyone know if there is a better way to do this?

Answer 1

It is no less hacked, in the sense that it will still require interaction from powershell, but the interaction code can be more accurate if you use (or can call): GetFirmwareType() .

This returns the FIRMWARE_TYPE enumeration registered here . I can’t believe that both functions are provided in Windows 8 and exported kernel32.dll, which Microsoft has documentation pointing to "using a dummy variable"!

Internally, GetFirmwareType calls NtQuerySystemInformation . I will delve into what he does, but I do not think that this will necessarily be enlightenment.

Unfortunately, this only works for PE4 (Windows 8), as these features were added only then.

Answer 2

It may be a little late, but if it is known that they work in WinPE, the following code should work:

 $isuefi = (Get-ItemProperty -Path HKLM:\System\CurrentControlSet\Control).PEFirmwareType -eq 2 

Answer 3

I don’t have a UEFI system to test it, but this article seems to imply a registry value there that you can query under PE to indicate in which mode it was loaded:

http://technet.microsoft.com/en-us/library/dn293283.aspx

Answer 4

It looks like the PE environment has a folder specific to the PE environment. In addition, the% TargetDir% variable, the TARGETDIR property , is described here.

Finally, you can check if you are running from X: there should also be a folder with the boot.wim file, which you can check. I believe the path will be X: \ Sources \ Boot.wim , but double check.

 if ( Test-Path "%TargetDir%\Windows\wpeprofiles" ) { Write-host "You're in Windows PE" } 

Answer 5

I don't know if this will help (based on a C # solution), but:

Win32_DiskPartition has the properties "Boot" (bool), "BootPartition" (bool) and "Type" (string). For my UEFI system, "Type" is returned as the string "GPT: System".

Now, for all bootable Win32_DiskPartitions boot files, they are the boot partition and have the specified type, determine if any of them are internal.

Hope this helps.