You can find the menuconfig options in Device Drivers -> Multi-device support (RAID and LVM) -> RAID support -> RAID-4/RAID-5/RAID-6 mode and Device mapper support -> RAID 4/5 target (EXPERIMENTAL)
You can find the menuconfig options in Device Drivers -> Multi-device support (RAID and LVM) -> RAID support -> RAID-4/ RAID-5/ RAID-6 mode and Device mapper support -> RAID 4/5 target (EXPERIMENTAL)