On Mon, Mar 10, 2014 at 7:59 PM, Arnd Bergmann [off-list ref] wrote:

quoted

arch/avr32/include/asm/io.h:#define IO_SPACE_LIMIT    0xffffffff
arch/frv/include/asm/io.h:#define IO_SPACE_LIMIT      0xffffffff

They have no MMU, and the code relies on the port number to match
both the virtual and the physical address. You could be right about
these, but I would guess that the code also needs some other
changes if we want to make it work on nommu kernels. It also depends
on whether the I/O bus address is the same as the CPU address, or
if it starts at bus address 0.

quoted

arch/m68k/include/asm/io_no.h:#define IO_SPACE_LIMIT 0xffffffff

This looks like a mistake, it should be smaller

io_no.h is for nommu.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds