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littlekernel / lk

LK embedded kernel
MIT License
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[build] make LK buildable with LLVM/Clang #322

Open pcc opened 2 years ago

pcc commented 2 years ago

Add an environment setting LLVM=1 that replaces usage of GNU tools with the LLVM equivalents.

Current status is that it builds on arm64 for QEMU with several warnings and then boots. I didn't hook up any other architectures but the arm64 setup should serve as a guideline.

travisg commented 2 years ago

Oh I just saw this after mentioning that should add support for LLVM. Will give it a go to make sure it works on all the arches. Seems like it's just for arm64 at the moment?

pcc commented 2 years ago

Yes, I'd expect this to fail on the other arches because it would need some changes to the other arch-specific makefiles. I'm currently only set up to build for arm64 (e.g. only have arm64 baremetal builtins library to hand) so I didn't touch the other arches.

pcc commented 1 year ago

Ping... it would be nice to land this so that I don't have to keep carrying it around when testing other patches (I don't have a compatible GCC installation on this machine).

travisg commented 1 year ago

Yah, will take a look. I need to resolve it against other arches and see how to keep that going. Also have some work recently with fpu enablement that this might intersect with.

On Thu, Jul 21, 2022 at 2:20 PM pcc @.***> wrote:

Ping... it would be nice to land this so that I don't have to keep carrying it around when testing other patches (I don't have a compatible GCC installation on this machine).

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travisg commented 1 year ago

One thing that might help is to break this CL into two parts. One is just stuff needed to get clang to compile and the second one would be build system config stuff. The former is a slam dunk, the latter might need a bit of thinking.

pcc commented 1 year ago

Sure, I was thinking that because this doesn't regress the other arches (you can still compile them with GCC) that wouldn't be a blocker to landing it at this point. Also some of the arches don't have LLVM backends at this point (microblaze, or1k) so this is probably never going to be "complete" in terms of arch support.

Would it help to have some kind of explicit error if you try to build an unsupported arch with LLVM=1?