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by dralley 2018 days ago
RHEL kernel versions are basically incomparable with vanilla kernel versions. They have hardware support and occasionally entire new features that have been backported from newer kernels in addition to the standard security & stability patches.

This means that RHEL 7 using a "kernel version" from 2014 will still work fine with modern hardware for which drivers didn't even exist in 2014.
2 comments
the8472 2018 days ago
That is not a good thing. RH frankenkernels can contain subtle breakage. E.g. the Go and Rust standard libraries needed to add workarounds because certain RH versions implemented copy_file_range in a manner that returns error codes inconsistent with the documented API because patches were only backported for some filesystems but not for others. These issues never occurred on mainline.

And for the same reasons that the affected users chose a "stable" and "supported" distro they were also unable to upgrade to one where the issue was fixed.

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dralley 2017 days ago
True, but it is a matter of weighing risks. I can't find it now, but I remember a few years ago there was a news story about how an update to Ubuntu had caused hospitals to start rendering MRI scan results differently due to differences in the OpenGL libraries. For those sorts of use cases, stable is the only option.
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smarx007 2017 days ago
I think this is a perfect use case for CentOS/RHEL as opposed to Ubuntu when the machine has only one job and nothing shall stand in its way, ie when you expect everything to be bug-for-bug compatible. But I fail to understand why a vendor of an MRI machine charging tens of thousands for installation/support cannot provide a supported RHEL OS which costs $180-350/yr in the cheapest config [1].

[1]: https://www.redhat.com/en/store/linux-platforms

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pezezin 2017 days ago
No, it doesn't. I will tell you my experience.

They bought some fancy new computers at work. Our procedures say to use CentOS 7, so we tried it, it ran like shit. Then we reinstalled CentOS 8, same. It worked, but the desktop was extremely slow. After much hair pulling I found the solution: add the elrepo-kernel repository, and update to kernel 5.x

No amount of backporting magic will make an old kernel work like a new kernel.

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