We have to remove the `#[naked]` attribute from `_start` for now, since it emits
a warning now when used with non-asm statements in the function body. For now,
just hope for the compiler's mercy to not emit code using the stack pointer
before we've actually set up a stack.
The RPi4 GPIO pull-up/pull down sequence is done differently than on the
RPi3. Switch to using the correct way.
Also, configure pull-ups for both UART pins.
Fixes#81
The GCC versions of `objdump` and `nm` seem to have better out-of-the-box
support (for AArch64). Demangling works better, and instructions in objdump are
presented as 4 bytes instead of 4 * 1 bytes, which helps a lot.
Hence, switch to the GCC versions for now until LLVM has caught up.
Detect if we run on Linux. If so, dockerize Makefile targets that need access to
USB devices. If we run on anything else, attempt to execute natively.
This will enable non-Linux Unixes like macOS to run the chainboot target, given
they install the needed Ruby dependencies.
`rustup target add aarch64-unknown-none-softfloat` is now a thing.
It is no longer required to build rust-std on-demand with `xbuild`.
This reduces compile-times significantly.
Sometimes, the RPi4 would not send a correct "OK" sequence of characters when
using `print!()`. Two separate `write_char()` calls seem to improve this
situation.
Not yet sure what the exact reason is, though.
Andre Richter