The ALSA guide does not mention the ALSA_CARDS variable in make.conf at all (nor ALSA_PCM_PLUGINS), which I believe is unfortunate. If the official standpoint is that these variables should be left unset then should at least that be clearly mentioned in the guide. However, I feel that it probably is wise to use them (at least ALSA_CARDS), which means that a short explanation of what they do seems appropriate. Perhaps even a list of possible values and their meanings (or a link to a suitable page).
Information on the ALSA_CARDS variable was removed at the request of the ALSA maintainers some time ago: http://sources.gentoo.org/viewcvs.py/gentoo/xml/htdocs/doc/en/alsa-guide.xml?r1=1.80&r2=1.81 If the ALSA team wants the ALSA_CARDS info in the guide, then we can put it back, but at the time it was clear they didn't want it to be documented. Same goes for ALSA_PCM_PLUGINS -- this does not need to be mentioned at all; it's only there for developers building embedded systems. For now I'm going to mark this bug as RESOLVED WON'T FIX, unless our ALSA maintainers say otherwise.
