Re: mmapping of /dev/zero always fails on darwin

[Derek Price]

Peter O'Gorman wrote:

> As you can see from this little snippet of gcc configure, you can't
> mmap /dev/zero on darwin.
>
>    AC_CACHE_CHECK([whether mmap from /dev/zero works],
>   gcc_cv_func_mmap_dev_zero,
>   [# Add a system to this blacklist if it has mmap() but /dev/zero
>    # does not exist, or if mmapping /dev/zero does not give anonymous
>    # zeroed pages with both the following properties:
>    # 1. If you map N consecutive pages in with one call, and then
>    #    unmap any subset of those pages, the pages that were not
>    #    explicitly unmapped remain accessible.
>    # 2. If you map two adjacent blocks of memory and then unmap them
>    #    both at once, they must both go away.
>    # Systems known to be in this category are Windows (all variants),
>    # VMS, and Darwin.


I don't suppose you could come up with a configure test or a short C
program that fails to compile (preferrably) or run (if necessary) to
spot this, short of actually switching on the system name or something
similar?

Regards,

Derek

-- 
Derek R. Price
CVS Solutions Architect
Ximbiot <http://ximbiot.com>
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