I've installed oss-freebsd-v4.0-1002-i386 on FreeBSD 6.2 /Gnome.2.16.3 and one of my apps - gMFSK - produces the following error:
sound_open_for_read: opensnd: ioctl: SNDCTL_DSP_NONBLOCK: m
It runs without problem when I remove OSS and use the snd_ich driver.