OTOH, the Linux SPARC V9 port is also suffering from these problems.  They
   get around this by not supporting 64-bit userland, like Solaris2.5-2.6, or
   so I hear.


not supporting meaning not providing?  do they run correctly compiled
64bit programs?  i noticed that most of the 'userland' in solaris 7 64bit
is still 32bit (very very few parts were)... of course the kernel has both
32bit and 64bit parts entirely.

is there a reason to use 64bit programs except where you *need* those bigger
pointers and longs?  i just see it wasting more memory than necessary... 


now that NetBSD/sparc is going to be ELF shortly, the ports can share the
programs.  now is when we really need libc_march shared libraries to ensure
that the right SPARC architecture uses the most efficient bits available..
again, like solaris does...