Somewhere between 12-Alpha1 and Alpha2, loader does no longer set hw.cpu_stdext_disable. This part of my loader.conf file. hw.cpu_stdext_disable=0x00100000 geli_ada0p5_keyfile0_load="YES" geli_ada0p5_keyfile0_type="ada0p5:geli_keyfile0" geli_ada0p5_keyfile0_name="/boot/encryption.key" aesni_load="YES" geom_eli_load="YES" vfs.root.mountfrom="zfs:zroot/ROOT/default" kern.geom.label.disk_ident.enable="0" kern.geom.label.gptid.enable="0" zpool_cache_load="YES" zpool_cache_type="/boot/zfs/zpool.cache" zpool_cache_name="/boot/zfs/zpool.cache" geom_eli_passphrase_prompt="YES" zfs_load="YES" kernels="kernel kernel.old kernel.orig