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Maybe >> you could most of mm defined even when CONFIG_MMU=n but keep >> MmWithUserAsync only available when CONFIG_MMU=y? >> > > Something like this, probably? But your choice ;-) Make CONFIG_RUST > select CONFIG_MMU is fine but the question is who is going to unselect > that at when? > In case it helps for the future: you should never select CONFIG_MMU. You can depend on CONFIG_MMU, but forcibly selecting it is wrong, because MMU support is a much broader system config decision than CONFIG_RUST, and must not be auto-selected. Also, some systems do not even have an MMU, and therefore should not have CONFIG_MMU nor CONFIG_RUST forcibly selected. thanks, John