Re: [PATCH] stub out is_swap_pte for !MMU

From: Andrew Morton
Date: Fri Feb 08 2008 - 17:10:13 EST


On Fri, 08 Feb 2008 15:41:42 -0600
Matt Mackall <mpm@xxxxxxxxxxx> wrote:

> Fix compile error on nommu for is_swap_pte
>
> Does it ever make sense to ask "is this pte a swap entry?" on a machine
> with no MMU? Presumably this also means it has no ptes too, right? In
> which case, it's better to comment the whole function out. Then when
> someone tries to ask the above meaningless question, they get a compile
> error rather than a meaningless answer.
>
> Signed-off-by: Matt Mackall <mpm@xxxxxxxxxxx>
>
> diff -r 50a6e531a9f2 include/linux/swapops.h
> --- a/include/linux/swapops.h Mon Feb 04 20:23:02 2008 -0600
> +++ b/include/linux/swapops.h Fri Feb 08 15:38:01 2008 -0600
> @@ -42,11 +42,13 @@
> return entry.val & SWP_OFFSET_MASK(entry);
> }
>
> +#ifdef CONFIG_MMU
> /* check whether a pte points to a swap entry */
> static inline int is_swap_pte(pte_t pte)
> {
> return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
> }
> +#endif
>

Seems contradictory. Is there _really_ a compilation error at present?
The changelog seems to imply otherwise and no compiler error output is
quoted and it all compiled OK for me on nommu superh.

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