I was thinking Oracle M-class gear and the late generation Fujitsu gear.
I have successfully tested GRUB on a PRIMEPOWER 250 with SPARC64 V+ (see [1]). The problem is that the Linux kernel doesn't work on any Fujitsu SPARC64 gear currently, not even on newer M-class machines (see [2]).
[1]: https://lists.debian.org/debian-sparc/2018/02/msg00074.html [2]: https://wiki.debian.org/Sparc64#Installing_the_Debian_SPARC64_Port Cheers, Frank