Subject: Re: [PATCH] asm-generic: Fix build when __set_fixmap is absent

From: Mark Rutland <[email-masked]>
Date: Tue, 9 Feb 2016 16:33:34 +0000

> >> include/asm-generic/fixmap.h:72:6: error: conflicting types for '__set_fixmap'
>     void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot);
>          ^
>    In file included from arch/um/include/asm/pgtable.h:11:0,
>                     from include/linux/mm.h:67,
>                     from include/linux/ring_buffer.h:5,
>                     from include/linux/trace_events.h:5,
>                     from include/trace/syscall.h:6,
>                     from include/linux/syscalls.h:81,
>                     from init/main.c:18:
>    arch/um/include/asm/fixmap.h:39:13: note: previous declaration of '__set_fixmap' was here
>     extern void __set_fixmap (enum fixed_addresses idx,
>                 ^

The conflict is the type of 'phys'. In arch/um that's an unsigned long
rather than a phys_addr_t as it is elsewhere.

If I convert that to a phys_addr_t the build goes along happily.

Should we change set_fixmap_offset back to a macro function for now, or
is it simple/correct to change arch/um to use phys_addr_t in
__set_fixmap?

Thanks,
Mark.