[Pkg-rust-maintainers] Bug#881846: Bug#881846: Bug#881846: rustc: FTBFS on armel

[Ximin Luo]

Ximin Luo:
> John Paul Adrian Glaubitz:
>> On 11/15/2017 07:16 PM, Tixy wrote:
>>> On Wed, 2017-11-15 at 18:53 +0100, John Paul Adrian Glaubitz wrote:
>>>> As for the atomics: What strikes me odd is that upstream claims that
>>>> ARMv6 is supported. But to my current knowledge, proper atomics were
>>>> only introduced with ARMv7.
>>>
>>> ARMv6 has 32-bit atomics (LDREX and STREX instructions), and ARMv6K adds
>>> 8-, 16-, and 64-bit versions.
>>
>> Ah, I guess my memory is wrong then. Were there any changes regarding
>> atomics in ARMv7 or was it just NEON that was introduced with ARMv7?
>>
> 
> Adrian Bunk (added to CC) has recently been trying to do a armel port:
> 
> <bunk> For buster armv5te_unknown_linux_gnueabi.rs seems to match the baseline. 
> [..]
> <bunk> infinity0: hits some armv6 assembler in compiler-rt, haven't yet look deeper into that issue
> 

By the way, I got all my information from this thread:
https://github.com/rust-lang/rust/issues/35590

Specifically this comment:
https://github.com/rust-lang/rust/issues/35590#issuecomment-240900710

"ARMv4 is tricky. It's possible to get atomic support working for it, but only on Linux. You'd need to use the kernel user helpers to implement various __sync_* functions that are going to be emitted by LLVM."

I haven't verified any of this myself, but he sounds like he knows what he's talking about and I've seen him porting other stuff to GCC in #gcc etc.

I'm also not sure what the ARMv5 situation is, if buster is going to be upgraded to that. Perhaps bunk has more details.

X

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