We discuss a generalized form of IIA/IIB supergravity depending on all R-R
potentials C-(p) (p = 0, 1,..., 9) as the effective field theory of type II
A/IIB superstring theory. For the IIA case we explicitly break this R-R dem
ocracy to either p less than or equal to 3 or p greater than or equal to 5,
which allows us to write a new bulk action that can be coupled to N = 1 su
persymmetric brane actions.
The case of eight-braves is studied in detail using the new bulk & brane ac
tion. The supersymmetric negative-tension branes without matter excitations
can be viewed as orientifolds in the effective action. These D8-branes and
O8-planes are fundamental in type I' string theory. A BPS eight-brave solu
tion is given which satisfies the jump conditions on the wall. It implies a
quantization of the mass parameter in string units. Also, we find a maxima
l distance between the two walls, depending on the string coupling and the
mass parameter. We derive the same results via supersymmetric flow equation
s.