Also, express this new maximum as a fraction of the kernel's address
space size rather than a constant so that increasing KVA_PAGES will
automatically increase this maximum. As a side-effect of this change,
kern.maxvnodes will automatically increase by a proportional amount.
While I'm here ensure that this change doesn't result in an unintended
increase in maxpipekva on i386. Calculate maxpipekva based upon the
size of the kernel address space and the amount of physical memory
instead of the size of the kmem map. The memory backing pipes is not
allocated from the kmem map. It is allocated from its own submap of
the kernel map. In short, it has no real connection to the kmem map.
(In fact, the commit messages for the maxpipekva auto-sizing talk
about using the kernel map size, cf. r117325 and r117391, even though
the implementation actually used the kmem map size.) Although the
calculation is now done differently, the resulting value for
maxpipekva should remain almost the same on i386. However, on amd64,
the value will be reduced by 2/3. This is intentional. The recent
change to VM_KMEM_SIZE_SCALE on amd64 for the benefit of ZFS also had
the unnecessary side-effect of increasing maxpipekva. This change is
effectively restoring maxpipekva on amd64 to its prior value.
Eliminate init_param3() since it is no longer used.
c84b8f6e0c