64-bit PowerPC cross-compilation

Greetings,

I am trying to use the Emdebian PowerPC toolchains for the ultimate
goal of cross-compiling 32-bit and 64-bit PowerPC kernels on an AMD64
host.  I installed gcc-4.4-powerpc-linux-gnu (and associated
packages), and was able to successfully build a 32-bit kernel, with
powerpc-linux-gnu- even playing nice with make-kpkg.

On the other hand, building a CONFIG_PPC64=y kernel fails early with:

kernel/bounds.c:1: error: -m64 not supported in this configuration

Indeed, any use of "powerpc-linux-gnu-gcc-4.4 -m64" produces that.  I
found libc6-ppc64-powerpc-cross and libc6-dev-ppc64-powerpc-cross, but
lib64gcc1-powerpc-cross seems to be missing from the Emdebian
archives.  But even after grabbing lib64gcc1_4.4.5-8_powerpc.deb and
converting it with dpkg-cross to
lib64gcc1-powerpc-cross_4.4.5-8_all.deb (and installing all three), no
luck.

Is there currently any way to compile 64-bit PowerPC binaries through
the powerpc-linux-gnu toolchain?  Am I missing something glaringly
obvious?

RF