On Tue, Feb 6, 2018 at 2:05 PM, Robin Murphy <robin.murphy@xxxxxxx> wrote: > > It looks like we have only one real arch (score) without IOMEM, and two > (s390 and tile) where it is possible to configure out, so it does seem like > a reasonable feature to assume. Maybe we could have something like > asm-generic/no-io.h to provide an "unimplemented" version of those > interfaces. Agreed, there is no use trying to optimize for any of those three cases: For s390, all new machines come with PCI, so distros will enable it all the time. Few users run their own kernels even on older machines. score has been de-facto unmaintained for a few years, and tile has recently been orphaned with the hardware platform being abandoned by Mellanox. Arnd