options options HWPMC_HOOKS device hwpmc device hwpmc_mips24k on some MIPS targets are default on. For example TPLINK TL-WR1043NDv1 router. This options are not needed for normal operation, but takes 4MB wired memory. This makes large difference with 32MB RAM total. No idea if such large RAM usage is normal. But i simply remove them, and i think it should not be put in default kernels.