[leave it to me to forget to include most of my point in the original
 message...]

Let's say you have a machine with 128MB of memory.  That machine ends up with
NKPDE = 32; KPDE_BASE (1) + KPDE_MAX (31).  That's 32 * 16MB or 512MB of space
for kernel maps.  An eighth of the total amount of memory the machine can
address at all, in fact.

That machine gets, by the current algorithm, bufpages = nbuf = 1716.  So it
tries to allocate 1716 * 64K or 112,459,776 bytes of memory.  Well, that's
quite a bit more than it needs, but it ought to fit into 512MB just fine.

Where does all of the address space go?

Thor