Tracking issue for CONFIG_MODULES on LoongArch

[xen0n]

Follow-up issue for #1787.

Currently one cannot build a working kernel with CONFIG_MODULES=y and with Clang/LLD, because of missing Clang support for __attribute__((model("extreme"))). This issue tracks the work towards support for said attribute and enabling modular LoongArch kernel builds.

Implementing this may require deep plumbing inside LLVM/Clang (straight down to LLVM IR-level addition), per the recent discussion, and I expect the relevant changes to hit LLVM 18 (LLVM 17 will branch later this month so it's probably not good to rush an LLVM IR change into it).

[heiher]

[RFC] Add per-global code model attribute

[nathanchance]

Is the plan for Linux to use the large code model attribute instead of extreme or will there be a follow up commit to add extreme for the kernel later?

[heiher]

Is the plan for Linux to use the large code model attribute instead of extreme or will there be a follow up commit to add extreme for the kernel later?

heiher@e540e0f

Perhaps there could be aliases to eliminate differences.

[xen0n]

Is the plan for Linux to use the large code model attribute instead of extreme or will there be a follow up commit to add extreme for the kernel later?

heiher@e540e0f

Perhaps there could be aliases to eliminate differences.

Yeah I'd suggest adding support for model("extreme") as alias of large in the LoongArch Clang frontend (if that's the proper way to go).

[heiher]

Fixed by:
llvm/llvm-project#72077
llvm/llvm-project#72078
llvm/llvm-project#72079

[nathanchance]

Indeed, I can confirm that with ToT LLVM, we are now able to build and boot ARCH=loongarch defconfig without disabling any configurations :)

I wonder if we can deal with #1941 now by setting the minimum supported version of clang for ARCH=loongarch to 18.0.0?

[xen0n]

Indeed, I can confirm that with ToT LLVM, we are now able to build and boot ARCH=loongarch defconfig without disabling any configurations :)

I wonder if we can deal with #1941 now by setting the minimum supported version of clang for ARCH=loongarch to 18.0.0?

Yeah I think so, as all that Huacai asked for is working defconfig builds, which we just achieved before the LLVM 18 code freeze.