I have a customer who says that mplayer (using OSS) does not work when he tries a kernel based on 2.6.23-rc4, but it works when he uses a kernel based on 2.6.21. Everything else is the same (including the version of alsa-lib), so I presume something broke in the OSS emulation in the kernel. Unfortunately, our git repositories for these trees are not compatible, so I can't use git-bisect to narrow the problem down.
Is it possible to back-level the ALSA support in the kernel itself? Can I just download ftp://ftp.alsa-project.org/pub/driver/alsa-driver-1.0.XX.tar.bz2 and follow the instructions in the INSTALL file?
If you update the kernel, are you supposed to use the latest alsa-lib as well? For a given kernel, how do I know what the right version of alsa-lib is?