Choosing a default text address for user programs for a new port

Good afternoon,

I'm trying to get a new port running (I'm currently trying to exec init
for the first time) and I'm wondering what I should use as the default
text address for user programs.  I searched the list archives a bit, but
didn't see anything particularly informative.

It seems like 0 is a bad choice, since it would make it hard to detect
NULL pointer reads.  I note that /sbin/init on my i386 box has text
starting at 0x08048100, but I don't know why it leaves all that space
after 0.

Suggestions, tips, or pointers to docs would be much appreciated.

Thanks!
--Glenn S.