Re: [OE-core] [RFC] rust: Upgrade 1.85.1->1.86.0

[Yash Shinde <Yash.Shinde@windriver.com>]

On 30-05-2025 08:02, Khem Raj wrote:
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> On 5/27/25 9:26 AM, Alexander Kanavin via lists.openembedded.org wrote:
>> On Tue, 27 May 2025 at 16:42, Yash Shinde <Yash.Shinde@windriver.com> 
>> wrote:
>>> Yeah, that's the reason.
>>>
>>> I am not sure how rust-lld is installed in ${D} now. A similar error 
>>> was
>>> previously resolved by using:
>>> "+TARGET_CC_ARCH +=
>>> "${LDFLAGS}""(https://git.yoctoproject.org/poky/commit/?id=cc24a0ff76f2e227cc3a0f478d078b2158299a80) 
>>>
>>>
>>> LDFLAGS are explicitly unset in rust recipe.
>>> (https://git.yoctoproject.org/poky/tree/meta/recipes-devtools/rust/rust_1.85.1.bb#n194) 
>>>
>>> I attempted to remove the "unset LDFLAGS" in rust recipe and exported
>>> TARGET_CC_ARCH as above, but that didn't work.
>>>
>>> Is there some different or recommended way to pass LDFLAGS to rust that
>>> I might be missing?
>>
>> The issue isn't about how to pass LDFLAGS. The issue is that something
>> triggers building all these additional things, including rust-lld, and
>> you need to narrow down how and where that happens, and how to go back
>> to the install set (and build times) we've had in 1.85. Please get to
>> the particular point where that decision happens.
>>
>> We can't just double the build times without a comprehensive,
>> convincing investigation.
>>
>
> Try adding
>
> [rust]
> lld = false
>
> to config.toml, but lld might speed up rust packages themselves. So
> perhaps this should be capped under a packageconfig or such, provided
> this works.
>
I investigated the commit histroy between 1.85.1 and 1.86 and found few 
commits related
to building a "self-contained" LLD (rust-lld)as part of rust bootstrap 
build.
This results additional installations during the builds.

Here are the commits and PRs:

https://github.com/rust-lang/rust/pull/135001
https://github.com/rust-lang/rust/commit/8744b44e6bde053f7656a3c727c968177ee8e4b6

Additionally, there's ongoing development to make LLD as the default 
linker for x86_64-unknown-linux-gnu.
https://github.com/rust-lang/rust/pull/140525

As Khem mentioned, setting lld = false in config.toml doesn't build LLD.
Furthermore, using "use-lld = false" ensures that LLD is not used as the 
default linker,
causing the build to fall back to the system's default linker. This 
restores the earlier behavior.
Also, the package QA error for rust-lld is not seen with this.

Regards,
Yash


>> Alex
>>
>