PowerMac G5 (Late 2005) Quad [dual dual] , SMP not working

Hello,

First some kudos - using either a prebuild netbsd-POWERMAC_G5 (NetBSD
9 prerelease) or a home-rebuild, single-CPU variant of
netbsd-POWERMAC_G5_11_2 (from -current CVS),  my PowerMac G5 (late
2005) Quad (dual-cpu dual-core) works fine, including (liquid)
cooling, network and SATA disk. This includes rebuilding some of
pkgsrc & the aforementioned kernel(s). (I have to load the kernel
directly instead of going through ofwboot, but that's not a problem,
and I got that to work with both netboot/NFS root and local disk
boot/root).

However, I soon as I try a multiprocessor-enabled kernel, it won't
boot. The assert at sys/arch/powerpc/pic/intr.c:561: "KASSERT(virq !=
0);" fails, and the kernel drops me in a debugger at least for the
11_2 variants.

I've also tried only defining cpu0 & cpu1 (with little hope) instead
of cpu*, but I get the same result.

From previous posts to the mailing list, this machine might not have
been tried before - I see reference to only the single-cpu dual-core
version for the 970MP. Is there anything that I can try/report to help
with getting better support for this particular beast? As the most
poweful PowerMac ever, it would be nice to get full SMP support :-)

Thanks in advance for any suggestion/help & cordially,

-- 
Romain Dolbeau