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A comment on Essence: Desktop operating system built from scratch. Parent comment

Re:Essence: Desktop operating system built from scratch by nodesocket on Saturday January 15, 2022 @09:49PM (#29952789)
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) {}.
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Re:Essence: Desktop operating system built from scratch by 8192kjshad09- on Saturday January 15, 2022 @10:11PM (#29952896)
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

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Re:Essence: Desktop operating system built from scratch by estebarb on Saturday January 15, 2022 @10:11PM (#29952899)
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...

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Re:Essence: Desktop operating system built from scratch by pjmlp on Sunday January 16, 2022 @03:02AM (#29954226)
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

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Re:Essence: Desktop operating system built from scratch by transitorykris on Saturday January 15, 2022 @10:06PM (#29952873)
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.
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Re:Essence: Desktop operating system built from scratch by asveikau on Sunday January 16, 2022 @01:13AM (#29953836)
An os kernel needs a lot of custom work for the hardware. Example: manipulating page tables, handling interrupts, making context switches work.
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