The feature is only on SPARC, not x86. Oracle killed in-house SPARC development in 2017, and they abandoned OpenSPARC after they acquired Sun, so it's effectively a dead architecture. The software won't work without the hardware to run it on.

Fujsitsu also does SPARC, and contrary to HP-UX, people still do buy Solaris.

EDIT:

https://www.oracle.com/servers/sparc/

https://www.fujitsu.com/global/products/computing/servers/un...

Finally, it is up to Intel and AMD to come up with hardware memory tagging, so far they have messed up all attempts, with MPX being the last short lived one.

It's good info, and I wouldn't rush a migration off of SPARC systems if I was already using them, but slow death is still death. It was already worrying that workstations were killed off by Sun before the Oracle acquisition; it seems quite clear that no one has been serious about spreading adoption of the architecture for more than two decades now.

Even Fujitsu has been moving away from SPARC. What was the last SPARC Fujitsu designed?

What matters is that they are still selling them.

Kind of. Atos still sell GCOS/GECOS mainframes, but they are Xeon boxes running emulators. Same with Unisys and MCP (which was written in an ALGOL and had bounds checked IIRC).