[nodesocket]

Curious, is porting complex C++ projects to arm64 just a matter of updating build/CI systems or does it actually involve changing core code and adding branches if (x64) {} ... if (arm64) {}.

[8192kjshad09-]

Most user-space code is not difficult to port. An operating system is much more work.

Take a look at https://github.com/torvalds/linux/tree/master/arch/arm64

[estebarb]

For common programs it's not very difficult, usually just recompile. But if it uses assembly then you are out of luck. Also if it requires a library that uses it.

For an OS it is different, you need to reimplement many parts: bootloader, drivers, task scheduler, virtual memory...

[pjmlp]

Like everything in computing it depends.

x86 and ARM don't same the same memory consistency model, so while managed languages do somehow protect their users from the differences, languages like C++ do expose it by default (unless you make use of the C++11 memory model APIs[0]).

So it depends how clever the lock-free kernel datastructure were written and other memory access assumptions.

[0] - https://en.cppreference.com/w/cpp/language/memory_model

[transitorykris]

All of the x86 assembly (see arch and boot/x86 dirs..) and any x86 assumptions being made elsewhere in the rest of the code is where the work is.

[asveikau]

An os kernel needs a lot of custom work for the hardware. Example: manipulating page tables, handling interrupts, making context switches work.