  The compact 7-manifold arising in the compactification of 11-dimensional
supergravity is described by the metric encoded in the vacuum expectation
values(vevs) in d=4, N=8 gauged supergravity. Especially, the space of
SU(3)-singlet vevs contains various critical points and RG flows(domain walls)
developing along AdS_4 radial coordinate. Based on the nonlinear metric ansatz
of de Wit-Nicolai-Warner, we show the geometric construction of the compact
7-manifold metric and find the local frames(siebenbeins) by decoding the
SU(3)-singlet vevs into squashing and stretching parameters of the 7-manifold.
Then the 11-dimensional metric for the whole SU(3)-invariant sector is obtained
as a warped product of an asymptotically AdS_4 space with a squashed and
stretched 7-sphere. We also discuss the difference in the 7-manifold between
two sectors, namely SU(3)xU(1)-invariant sector and G_2-invariant sector. In
spite of the difference in base 6-sphere, both sectors share the 4-sphere of
CP^2 associated with the common SU(3)-invariance of various 7-manifolds.
