I'm writing my own bootloader and I want to be able to boot Windows (and Linux).
bootmgfw.efi is the windows bootloader and I'm trying to load and start it with UEFI functions LoadImage() and StartImage(), but after calling StartImage() on it, I get EFI_INVALID_PARAMETER error, even though I checked that the image handle is valid and LoadImage() didn't return an error status.
I am able to start other EFI applications with the same code but bootmgfw.efi is the only one that doesn't start, though I am able to start it in the UEFI Shell just fine.
Here is some context to show what I do. I'm using POSIX-UEFI to write my code.
// Opening the root volume
efi_handle_t device = LIP->DeviceHandle;
efi_simple_file_system_protocol_t* fsProtocol = NULL;
efi_guid_t fsGuid = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID;
BS->OpenProtocol(device, &fsGuid, (void**)&fsProtocol, IM, NULL, EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL);
efi_file_handle_t* rootDir = NULL;
fsProtocol->OpenVolume(fsProtocol, &rootDir);
// Opening the bootloader file
efi_file_handle_t* winBootMgrHandle = NULL;
uint16_t path[] = u"EFI\\Microsoft\\Boot\\bootmgfw.efi";
rootDir->Open(rootDir, &winBootMgrHandle, path, EFI_FILE_MODE_READ, EFI_FILE_READ_ONLY);
// Getting file info for the file size
efi_guid_t infoGuid = EFI_FILE_INFO_GUID;
efi_file_info_t fileInfo;
uintn_t infoSize = sizeof(fileInfo);
winBootMgrHandle->GetInfo(winBootMgrHandle, &infoGuid, &infoSize, &fileInfo);
// Reading the file into a buffer
uintn_t winBootMgrSize = fileInfo.FileSize;
char* winBootMgrData = (char*)malloc(winBootMgrSize + 1);
winBootMgrData[winBootMgrSize] = 0;
winBootMgrHandle->Read(winBootMgrHandle, &winBootMgrSize, winBootMgrData);
// Loading and starting the image
efi_handle_t imgHandle;
BS->LoadImage(0, IM, LIP->FilePath, winBootMgrData, winBootMgrSize, &imgHandle);
BS->StartImage(imgHandle, NULL, NULL); // returns -2: invalid parameter
I don't understand why I get this error and how it can be fixed. I want to know how to fix this error and start this windows bootloader.
I got the solution here. Turns out I really was passing the incorrect device path to LoadImage().
https://forum.osdev.org/viewtopic.php?f=1&t=50623