According to discussions on the Gentoo [1] and Fedora [2] forums, i686 without SSE2 could be broken in some packages in subtle ways. One is that the stack alignment changed from 4 bytes to 16 bytes, another is long NOPs, another is that some software seems to require SSE2 on i686 like rustc or qt.
Even those platforms that claim to build for i686, I’m not sure if everything works correctly on pre-SSE2 (Pentium Pro, Pentium III, older Pentium 4) CPUs. And I don’t think any of the Linux distributions will actually run on a i386, i486 or i586 as i686 is almost required to have multithreading without busy waits.
The BSDs I don’t know about, but it’s a fair number of distributions that seem to support older x86 CPUs you posted. I didn’t know there would be so many. I couldn’t find Linux Mint though.
Even those platforms that claim to build for i686, I’m not sure if everything works correctly on pre-SSE2 (Pentium Pro, Pentium III, older Pentium 4) CPUs. And I don’t think any of the Linux distributions will actually run on a i386, i486 or i586 as i686 is almost required to have multithreading without busy waits.
The BSDs I don’t know about, but it’s a fair number of distributions that seem to support older x86 CPUs you posted. I didn’t know there would be so many. I couldn’t find Linux Mint though.
[1]: https://forums.gentoo.org/viewtopic-t-1087434.html?sid=4b682... [2]: https://lists.fedoraproject.org/archives/list/devel@lists.fe...