efi/fdt: don't expose fdt to kernel

There is a check that if fdt is stub when ACPI table initialized in
linux kernel [1]. So, if full fdt is given, fdt will be used insdead of
ACPI. It is aginst our primary goal to use UEFI. So, full fdt can't
be given here. For simplicity, just neglict it here.

It can be improved by making a stub fdt and pass it through configuration
table. Maybe later.

Fixes: #261
Signed-off-by: Jianyong Wu <[email protected]>

[1] https://github.com/torvalds/linux/blob/d528014517f2b0531862c02865b9d4c908019dc4/arch/arm64/kernel/acpi.c#L203

src/efi/mod.rs

@@ -614,7 +614,6 @@ pub extern "efiapi" fn install_configuration_table(guid: *mut Guid, table: *mut
 
     for entry in ct.iter_mut() {
         if entry.vendor_guid == unsafe { *guid } {
-            entry.vendor_table = table;
             if table.is_null() {
                 entry.vendor_guid = INVALID_GUID;
                 entry.vendor_table = null_mut();
@@ -1115,6 +1114,8 @@ pub fn efi_exec(
     let mut ct_index = 0;
 
     // Populate with FDT table if present
+    // To boot with ACPI, we can't offer full fdt. Simply, neglect it. See https://github.com/torvalds/linux/blob/d528014517f2b0531862c02865b9d4c908019dc4/arch/arm64/kernel/acpi.c#L203
+    #[cfg(not(target_arch = "aarch64"))]
     if let Some(fdt_entry) = info.fdt_reservation() {
         ct[ct_index] = efi::ConfigurationTable {
             vendor_guid: Guid::from_fields(