Ubuntu 26.04 Resolute CPU ISA level error

[swurvin-cyber]

Bug Overview

Hello, this is not a bug per say, but the latest ubuntu release 26.04 Resolute, Nginx will not start and produces the error message "CPU ISA level lower than required". Seems the packages were compiled with the latest processors in mind and not backwards compatible with the older processors.

Expected Behavior

Expected behavior, be compatible with older hardware.

Steps to Reproduce the Bug

After installing the latest stable release from your repository. I execute, service start nginx and I receive error "CPU ISA level lower than required".

Environment Details

Ubuntu 26.04 "Resolute Raccoon" Processor Xeon E3 1240V3.

Additional Context

No response

[thresheek]

Thanks @swurvin-cyber for raising this.

As far as I understood, indeed, Ubuntu 26.04 cloud images (which we use to build nginx on AWS) now come with amd64v3 by default, and there are no plain amd64 images anymore, from https://documentation.ubuntu.com/public-cloud/all-clouds-explanation/architecture-variants/#supported-variants:

for official Ubuntu images available to launch within public cloud platforms, only v3-enabled images will be available (again, for 26.04 Resolute Raccoon and forward). These amd64v3-enabled images will be published and supported under the “amd64” architecture name. Legacy amd64 images for public cloud platforms will not be published or supported for 26.04 and forward.

[thresheek]

As it goes, I dont think there is a good way for us to provide x86-64-v2 or earlier builds for Ubuntu 26.04 now.

There are two reasons:

• to create an x86-64-v2-compliant build environment, we'd need to reinstall all the packages on a freshly launched VM, reboot, and then re-populate with our build dependencies. This is doable, but it's kinda horrible to support for the whole lifetime of Ubuntu 26.04 which is currently +5 years from now.
• even if we will succeed on producing the x86-64-v2 builds, we don't have a way to test if they actually conform to v2 as we don't have the hardware nor the pristine Ubuntu 26.04 environment to test it.

[thresheek]

Note that while this particular issue is about Ubuntu 26.04, other OSes had recently made a similar (actually, even stricter) change to only provide x86-64-v3 builds - e. g. RHEL 10.

[swurvin-cyber]

Thank you for the thorough explanation. My apologies for my delayed response. I can always make do with Ubuntu 24.04 or give the official ubuntu nginx package a go.

[thresheek]

Sure. I'm going to keep this open for visibility. Maybe Ubuntu would come to their senses and fix the cloud images eventually..

[tanja84dk]

When will this be fixed?
Like I even installed a fresh Ubuntu 26.04 from their official server iso ( VM ) and then nginx gives that error

A complete fresh ubuntu vm from their iso and installed nginx from your repo

Jul 22 16:55:17 testserver systemd[1]: Starting nginx.service - nginx - high performance web server...
░░ Subject: A start job for unit nginx.service has begun execution
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ A start job for unit nginx.service has begun execution.
░░
░░ The job identifier is 1116.
Jul 22 16:55:17 testserver nginx[1800]: /usr/sbin/nginx: CPU ISA level is lower than required
Jul 22 16:55:17 testserver systemd[1]: nginx.service: Control process exited, code=exited, status=127/n/a
░░ Subject: Unit process exited
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ An ExecStart= process belonging to unit nginx.service has exited.
░░
░░ The process' exit code is 'exited' and its exit status is 127.
Jul 22 16:55:17 testserver systemd[1]: nginx.service: Failed with result 'exit-code'.
░░ Subject: Unit failed
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ The unit nginx.service has entered the 'failed' state with result 'exit-code'.
Jul 22 16:55:17 testserver systemd[1]: Failed to start nginx.service - nginx - high performance web server.
░░ Subject: A start job for unit nginx.service has failed
░░ Defined-By: systemd
░░ Support: http://www.ubuntu.com/support
░░
░░ A start job for unit nginx.service has finished with a failure.
░░
░░ The job identifier is 1116 and the job result is failed.

Or what webserver should people then move to if you won't fix it ( since you are then keeping it broken on purpose )

[thresheek]

Hi @tanja84dk, unfortunately there is no fix for that issue for Ubuntu 26.04 packages from nginx.org repos. The only way forward is to upgrade the hardware to support x86-64-v3 variants.

[tanja84dk]

Well you cant upgrade the hardware a vm says it is

But thank tyou very much for verifying that nginx and a project and payed product are completely EOL

[imyller]

No matter what your build environment is just compile the Ubuntu packages with with -march=x86-64-v2. Problem solved.

As far as I can see Nginx does not really use v3 specific SIMD features internally so imposing this packaging limit for huge number of VMs that are limited to v2 is not justified.

[Jean-Daniel]

No matter what your build environment is just compile the Ubuntu packages with with -march=x86-64-v2. Problem solved.

Indeed, you can easily build v2 compatible software on any architecture (v3, v4). This is just a compiler flag.

As far as I can see Nginx does not really use v3 specific SIMD features internally so imposing this packaging limit for huge number of VMs that are limited to v2 is not justified.

You don't have to explicitly use SIMD to benefit from v3 features. The compiler is smart enough to optimise the code to use v3 instructions and improve performance when possible. That said, v3 packages should be opt-in and distributed as a micro architecture variant, not has the main package.