is there a plan to add armv7 support to cpufeatures?

[x3ccd4828]

[tarcieri]

We can potentially add it. Is there a specific feature you're interested in?

[x3ccd4828]

I was trying to compile lighthouse (https://github.com/sigp/lighthouse) for armv7 target and the compile halts because of the requirement. I haven't had a chance to look into what that project needs from cpufeatures or how it's used.

I was looking around cpufeatures how to add armv7 but without any features just to allow the target compile to not fail. Is there somewhere, in particular, I should look?

[tarcieri]

If cpufeatures is breaking builds, it's being misused.

It should only be used on CPU architectures where it's supported, specifically for detecting architecture-specific features, like this:

https://github.com/RustCrypto/block-ciphers/blob/48242cc/aes/Cargo.toml#L19-L20

[x3ccd4828]

It is not breaking any builds the project i liked above currently doesn't support armv7, but i wanted to take a stab at it and see what modifications are needed to compile it for armv7.

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On Sun, Mar 19, 2023, 6:41 AM Tony Arcieri ***@***.***> wrote: If cpufeatures is breaking builds, it's being misused. It should only be used on CPU architectures where it's supported, specifically for detecting architecture-specific features, like this: https://github.com/RustCrypto/block-ciphers/blob/48242cc/aes/Cargo.toml#L19-L20 — Reply to this email directly, view it on GitHub <#850 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADYH4CB6MV5R7L2T5H3NCTW44EKBANCNFSM6AAAAAAV7X6QME> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[tarcieri]

The existing ARM code needs to be extended to ARMv7.

It should hopefully be relatively straightforward, although all of the current supported instructions on ARM are ARMv8-specific, so those need to be disabled on ARMv7 targets.

It would probably make sense to implement at least one instruction that can be detected. You could do neon, which would always be auto-enabled on ARMv8 targets.

[x3ccd4828]

Ok, thank you i will take a look, i might post questions here if i get confused.

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On Sun, Mar 19, 2023, 9:10 AM Tony Arcieri ***@***.***> wrote: The existing ARM code needs to be extended to ARMv7. It should hopefully be relatively straightforward, although all of the current supported instructions on ARM are ARMv8-specific, so those need to be disabled on ARMv7 targets. It would probably make sense to implement at least one instruction that can be detected. You could do neon, which would always be auto-enabled on ARMv8 targets. — Reply to this email directly, view it on GitHub <#850 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADYH4G5BJREBKRL45FMU6DW44VWXANCNFSM6AAAAAAV7X6QME> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[tarcieri]

See #403 as a previous attempt at neon feature detection

[gram-signal]

I'm currently interested in detecting if https://doc.rust-lang.org/core/arch/arm/fn.vmull_p8.html is available.

Are folks actively working on this?

[tarcieri]

Sounds like you want to detect neon which sounds worthwhile.

No one is currently working on it to my knowledge. What platforms are you intending to support? Linux?