How to build a unified kernel for aarch64?

[Zameer Manji <zmanji@xxxxxxxxx>]

Hello,

I have noticed there exists a systemd-stub for aarch64, the file
is located at `/usr/lib/systemd/boot/efi/linuxaa64.efi.stub`.

The manpage instructs users to use `objcopy` to build the unified
kernel from the stub. However when I use objcopy I get the following
error:

```
objcopy: /usr/lib/systemd/boot/efi/linuxaa64.efi.stub: file format not
recognized
```
I also noticed the GNU binutils bug tracker indicates that PE executables on
ARM are not yet supported for objcopy [0].

How do systemd developers build the unified kernel on aarch64? Is there
an alternative toolchain used?

[0]: https://sourceware.org/bugzilla/show_bug.cgi?id=26206
-- 
Zameer Manji