[RFC PATCH 00/10] Improve ARM target's support for LLVM toolchain

Sam Edwards cfsworks at gmail.com
Sun May 21 06:59:26 CEST 2023

On 5/20/23 22:26, Heinrich Schuchardt wrote:
> Hello Sam,

Hi Heinrich! Good to hear from you.

> I guess the documentation and the CI testing would also have to be adjusted.

Ah, yeah, those are going to be big things for me to look at when this 
series starts to mature out of the RFC phase. CI is definitely important 
so that the hard-won compatibility doesn't just decay away. :)

> What about non-ARM architectures?

If there's a groundswell of demand for building U-Boot on LLVM, I'd be 
willing to collaborate with others on getting the other architectures up 
to parity with GNU. But since the linker scripts, relocation thunks, 
sections, and whatnot are all arch-specific, I'm only focusing on ARM 
for now (which is both the arch I need and one of the more common ones).

Is there a particular arch you'd like to see next? It seems everything 
U-Boot supports is supported by LLVM, except for Microblaze, NIOS2, and SH.

> Could you, please, describe how built with lld so that reviewers can test it.

I've been building with:

nice make CC='clang --target=armv7l-none-eabi' \
   LTO_FINAL_LDFLAGS=-fuse-ld=lld LD=ld.lld OBJCOPY=llvm-objcopy

...though mostly at this stage I'm just hoping for folks to confirm that 
this patchset causes no regressions in their existing GNU environments. 
(Feedback from LLVM-land would be appreciated nonetheless, though!!!)

> I find reviewing hard when receiving only 3 out of 10 patches.

Oof sorry about that. I haven't actually joined the U-Boot mailing list 
yet so the other patches are probably caught in the moderation queue. I 
guess wait for moderation approval and see if the other 7 arrive then -- 
I can resend the whole series to you specifically if not.


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