How to access the 64-bit registry from a 32-bit Powershell instance?

Question

If you launch a 32-bit instance of Powershell (%SystemRoot%\\syswow64\\WindowsPowerShell\\v1.0\\powershell.exe), then the registry provider only sees the limited 32-bit part

Answer 1

To extend Milan Gardian's answer, use this function for small code blocks:

function RunAs-64Bit ([ScriptBlock]$scriptblock)
{
    [string]$code = 'using System.Diagnostics; static class Program { static int Main(string[] args) { ProcessStartInfo i = new ProcessStartInfo("powershell", args[0]); i.UseShellExecute = false; using(Process p = Process.Start(i)) { p.WaitForExit(); return p.ExitCode; } } }'
    [string]$exeName = $env:temp + '\' + [System.IO.Path]::GetRandomFileName() + '.exe';
    $params = New-Object 'System.CodeDom.Compiler.CompilerParameters'; 
    @('mscorlib.dll',  'System.dll', ([System.Reflection.Assembly]::GetAssembly([PSObject]).Location)) | %{ $params.ReferencedAssemblies.Add( $_ ) } | Out-Null
    $params.GenerateExecutable      = $true
    $params.GenerateInMemory        = $false;
    $params.CompilerOptions         = '/optimize';
    $params.OutputAssembly          = $exeName;
    $params.TreatWarningsAsErrors   = $false;
    $params.WarningLevel            = 4;

    $csprovider = New-Object 'Microsoft.CSharp.CSharpCodeProvider'; #disposable
    try {
        $compileResults = $csprovider.CompileAssemblyFromSource($params, $code)
        $errors = $compileResults.Errors | ?{ -not $_.IsWarning }
        if ($errors.Count -gt 0) 
        {
            Write-Host -f red 'Compiler errors are found.'
            foreach ($output in $compileResults.Output) { Write-Host -$output }
            foreach ($err in $errors) { Write-Host -f red $('Compile Error: ' + $err); }            
        }
        else 
        {
            $compileResults.Errors | %{ Abr-Write-UtilLog 'Util Get assembly from code' $('Compile Warning: ' + $_); }            
            $assembly = $compileResults.CompiledAssembly
            $commandParam = '-encodedCommand  ' + [System.Convert]::ToBase64String([System.Text.Encoding]::UNICODE.GetBytes($scriptblock));
            &$exeName $commandParam
        }
        Remove-Item -force $exeName -ErrorAction 'SilentlyContinue';
    } finally{
        $csprovider.Dispose();
        Remove-Variable 'csprovider';
    }
}

Now use this function to run any scriptblock (as long as it is not too big) in 64-bit mode when 64-bit mode is available