My last post here wrote about a SPARC userland emulator.
It's now in better shape. The latest big bug was that I was mishandling the case where a process vforks and the child, while still borrowing the parent's VM, expands the data segment with sbrk. (There have also been a handful of lesser bugs.)
It's now about a week into a build of the NetBSD 1.4T world and hasn't shown any signs of trouble. I'm optimistic.
I've also fired up my old VAX emulator (it emulates a KA630, the MicroVAX-II CPU, with a very few peripherals). I have the (emulated) VAX running diskless off my house network's NFS server. I set that one to doing its own build of the NetBSD 1.4T world. It's now two and a half days into that build, and, while it's building from a slightly different source tree, it appears to be running somewhere around 15-25 percent faster than the emulated SPARC, even though the VAX emulator is emulating the whole thing, including the privileged portions of the machine; it's running real NetBSD/vax, not the userland-only style of emulation the SPARC emulator implements. (EDIT: Also, the SPARC emulator is running on a 2.5GHz Xeon E5420, while the VAX emulator is running on a 2.2GHz Athlon 64 X2 that's powernow-slowed to 1GHz.)
This now has me wanting to get assorted other non-x86/x64 hardware out of storage and running! Time was, I had something like ten ports across seven CPU architectures running (or in runnable shape, needing only to be turned on). I doubt I will have the various resources to do very much of that anytime soon, though.
A list from memory: sun3 mac68k next68k vax i386 amd64 sparc sparc64 macppc alpha, of which the first three use the same CPU architecture. I'm fairly sure there was a second case of two ports using the same CPU architecture, hence another port in the list, but can't recall details; those memories are something like a decade old. And, even if I had the time, physical space, and electrical infrastructure, I'm not sure I still have working hardware for all those. (The only ones I'm reasonably confident I have working hardware for are sun3 alpha i386 amd64 sparc sparc64 macppc. There may be others—HP-PA, MIPS, and ARM are the most likely candidates—but they are definitely question marks at present.)