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Ubuntu 25.10 Raises RISC-V Profile Requirements

(www.omgubuntu.co.uk)
126 points bundie | 3 comments | 01 Jul 25 08:32 UTC | HN request time: 0.631s | source
1. londons_explore ◴[05 Jul 25 07:17 UTC] No.44470723[source]▶
Why can't these older processors be supported via a software shim for unrecognised instructions?

It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all.

replies(2): >>44471147 #>>44471356 #
2. snvzz ◴[05 Jul 25 08:43 UTC] No.44471147[source]▶
>Why can't these older processors be supported via a software shim for unrecognised instructions?

It can.

It's just this shim is out of scope for Ubuntu.

Refer to opensbi instruction emulation.

>It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all.

With features like vector instructions or pointer masking, we're talking a non-trivial slowdown.

3. camel-cdr ◴[05 Jul 25 09:28 UTC] No.44471356[source]▶
> It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all.

The difference on geekbench is 2x and not every benchmark has been optimized for RVV yet: https://browser.geekbench.com/v6/cpu/compare/10681749?baseli... (same hardware, one using the newer geekbench version that can take advantage of RVA22+V)