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[edit] Technical point

It could be interesting to outline the difference with emul-* packages (which, sincerely, I missed)

[edit] Tested apps

Regarding google-earth:

for me, it was lib32-gtk2, lib32-libsm and lib32-nvidia-utils (qt not required). Installer complained about libxml2 being 64bit, but continued (while libsm was a showstopper).