Support UEFI OS

[jclab-joseph]

Adds support for UEFI OS.

• Working minimal
• findGlobals
• Refactoring
• exit
• amd64
• smoke test
• target.json

not goal

• i386
• arm64 (TODO)

Usage :

tinygo build -target uefi-amd64 -o test.efi main.go

[aykevl]

Did a quick pass over the code (not a full review).

My main comment is this: can you make this more like any other baremetal target instead of making it its own thing besides baremetal and regular OSes? A baremetal target is much easier to maintain than what you have here (for example, the existing Nintendo Switch support is more work than any weird chip someone added support for years ago).

Also, please add a smoke test so we can see how it works.

[aykevl]

This looks like it will be a huge PR, so I suggest working on ways to simplify it. It can only be merged if it is maintainable, and right now it's so invasive I honestly don't want to merge it like this.

• Don't copy code like you did for findGlobals. Instead, find ways to reuse it. For example, you can move it to a new gc_windows.go file that is compiled in both Windows and UEFI.
• Do not make this a new GOOS. Instead, create targets/uefi.json that sets all the necessary properties (and adds at least the uefi and baremetal build tags). This probably means using GOOS=linux, like all the other baremetal targets. Then you can compile for UEFI using tinygo build -target=uefi ....
• Add a smoke test to GNUmakefile (there are lots of smoke tests already in there).

(To be clear: there is a difference between big and invasive. Right now it modifies many parts that shouldn't need to be modified by a PR that adds a new build target. If you need to use many lines of code to implement UEFI support, that's fine as long as it doesn't affect the common code too much).

[jclab-joseph]

Yes, it's not a good looking code right now.
It's a work in progress and needs a lot of refactoring.
Your opinion will help me a lot!

GOOS=linux is required, but with the exception uefi should use task_stack_windows_amd64 instead of task_stack_linux_amd64 . Cannot change name of task_stack.s without changing target.go.
I'm sorry. It was my mistake. It's being edited.