The kernel options that control use of a memory disk (ramdisk) have
been defopt'ed.  This probably only affects people building
installation media, or possibly kernels for diskless machines.

But if your kernel config uses a memory disk, you will need to re-run
config and then run `make depend'.

The kernel option 'MINIROOTSIZE', which controls the default ramdisk
size, hasn't yet been defopt'ed.