The Problem: Parameters such as HAVE_MMX appear in config.mak with value = auto, a recent-ish change in libavcodec's Makefile makes compilation of mmx and others depend on ifdef HAVE_MMX. When that variable is left defined as "auto", the build system tries to build MMX and SSE code on sparc64, and others. Other suspicious things can be found with 'grep auto config.mak' after configure. The patch: Unset _mmx & co if not on x86, unset altivec if not on ppc|powerpc, unset some arm parameters if not on arm. Fixes the compile on sparc64/netbsd and sparc64/freebsd, and keeps mmx/sse on x86_64 and x86_32. Is it the right place to unset, does it break crosscompilation? I don't know..