For older SPARC processors, operating system choice is limited to Solaris and other operating systems from the time of manufacture. Newer sun4u/sun4v 64-bit chips are supported by NetBSD, OpenBSD, and Linux however. What OS are you running on your SPARC machines? Are they doing work continuously or powered up only for testing?
All my machines are 64-bit and I'm trying to run modern software on all of them. My Sun Blade 150 (UltraSPARC IIi+) runs Debian sid as a workstation for fixing bugs with Linux userland software. A Sun Fire T1000 (T1) is running OpenBSD 6.9 and mostly sees work as a LDOM test bed however I'm currently trying to get Debian working without the help of an optical drive. Finally my pair of Sun Enterprise T5440s (4x T2+ each) are in storage waiting on a dedicated circuit. They run OpenBSD to take advantage of the LDOM support with Solaris & Debian guests.
In trying these operating systems, OpenBSD is very stable but the LDOM support has been broken for the past few releases (since 6.3). It's also an unsupported platform for LLVM, which means programming language support is more limited. Debian on sparc64 is a supported LLVM target, but there's no support for configuring LDOMs and only the "unstable" distribution works. I haven't tried NetBSD. There are compromises for any operating system running on these machines, so what compromises did you make?
All my machines are 64-bit and I'm trying to run modern software on all of them. My Sun Blade 150 (UltraSPARC IIi+) runs Debian sid as a workstation for fixing bugs with Linux userland software. A Sun Fire T1000 (T1) is running OpenBSD 6.9 and mostly sees work as a LDOM test bed however I'm currently trying to get Debian working without the help of an optical drive. Finally my pair of Sun Enterprise T5440s (4x T2+ each) are in storage waiting on a dedicated circuit. They run OpenBSD to take advantage of the LDOM support with Solaris & Debian guests.
In trying these operating systems, OpenBSD is very stable but the LDOM support has been broken for the past few releases (since 6.3). It's also an unsupported platform for LLVM, which means programming language support is more limited. Debian on sparc64 is a supported LLVM target, but there's no support for configuring LDOMs and only the "unstable" distribution works. I haven't tried NetBSD. There are compromises for any operating system running on these machines, so what compromises did you make?