Could someone with more gdb clue than me please verify the thread-support code?
Apparently only i386 has it in gdb5.3 now, and it's not clear to me how it
should be rolled forward from the previous changes.

Looking for example at sparcnbsd-nat.c there is a prominent comment:

/* NOTE: We don't bother with any of the deferred_store nonsense; it
   makes things a lot more complicated than they need to be.  */

IIUC the old thread support code just calls "the defered_store nonsense",
and now the calls need to be changed to sparcnbsd_fill_reg32 and 
sparcnbsd_supply_reg32 calls (and friends) - but how?

Martin