loader.efi does not boot on Lenovo Yoga C630

[Hiroo Ono]

Hello,

I am trying to install FreeBSD/aarch64 to Lenovo Yoga C630 (81JL0012JP).
It has Snapdragon 850 as the processor.

I tried the 13.0R image, the UEFI BIOS recognizes the EFI partition,
but loader.efi does not start at all. The screen stays blank.
I added the following code to efi_main(), but still there is no text
output.

diff --git a/stand/efi/loader/efi_main.c b/stand/efi/loader/efi_main.c
index fa3c765c3..f5174ec23 100644
--- a/stand/efi/loader/efi_main.c
+++ b/stand/efi/loader/efi_main.c
@@ -91,6 +91,10 @@ efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE 
*system_table)
                (void)console_control->SetMode(console_control,
                    EfiConsoleControlScreenText);

+       status = ST->ConOut->TestString(ST->ConOut, (CHAR16 *)L"Test\r\n");
+       if (status == EFI_SUCCESS)
+               ST->ConOut->OutputString(ST->ConOut, (CHAR16 
*)L"Test\r\n");
+
        heapsize = 64 * 1024 * 1024;
        status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
            EFI_SIZE_TO_PAGES(heapsize), &heap);


For other UEFI applications, grub2 works and UEFI Shell of EDK II does not 
work.
Is there anything I can do to let loader.efi run?