Bootloader For Windows 10 May 2026

[org 0x7c00] start: mov si, msg call print hlt print: lodsb or al, al jz done mov ah, 0x0e int 0x10 jmp print done: ret

// Build full device path (file path appended) EFI_DEVICE_PATH_PROTOCOL *FullPath = FileDevicePath(LoadedImage->DeviceHandle, L"\\EFI\\Microsoft\\Boot\\bootmgfw.efi"); bootloader for windows 10

// Open Windows Boot Manager file Status = Root->Open(Root, &File, L"\\EFI\\Microsoft\\Boot\\bootmgfw.efi", EFI_FILE_MODE_READ, 0); if (EFI_ERROR(Status)) Print(L"Error: bootmgfw.efi not found\n"); return Status; [org 0x7c00] start: mov si, msg call print

// Get device path of the file Status = gBS->HandleProtocol(LoadedImage->DeviceHandle, &gEfiDevicePathProtocolGuid, (VOID**)&FilePath); if (EFI_ERROR(Status)) return Status; [org 0x7c00] start: mov si

EFI_STATUS Status; EFI_LOADED_IMAGE_PROTOCOL *LoadedImage; EFI_SIMPLE_FILE_SYSTEM_PROTOCOL *Volume; EFI_FILE_PROTOCOL *Root, *File; EFI_DEVICE_PATH_PROTOCOL *FilePath; EFI_HANDLE BootMgrHandle;

// Open simple file system on the same device (ESP) Status = gBS->HandleProtocol(LoadedImage->DeviceHandle, &gEfiSimpleFileSystemProtocolGuid, (VOID**)&Volume); if (EFI_ERROR(Status)) return Status;

// Load and start bootmgfw.efi Status = gBS->LoadImage(FALSE, ImageHandle, FullPath, NULL, 0, &BootMgrHandle); if (EFI_ERROR(Status)) return Status;