Re: [Xen-devel] [PATCH] libxc portability fixes

["Christoph Egger" <Christoph.Egger@xxxxxxx>]

On Wednesday 19 September 2007 16:49:49 Vincent Hanquez wrote:
> On Wed, Sep 19, 2007 at 04:32:59PM +0200, Christoph Egger wrote:
> > MAP_ANONYMOUS is the proprietary thing.
>
> which "proprietary thing" ?
>
> > The glibc people
> > should know that and should deprecate MAP_ANONYMOUS instead.
>
> solaris has deprecated MAP_ANON as well.

Oh, SystemV Unix has MAP_ANONYMOUS?
BSD-Unix only has MAP_ANON.

> > They should also document that the fd argument must be
> > -1 when MAP_ANON is specified to match the Unix behaviour.
>
> ----------
> MAP_ANONYMOUS
>
> The mapping is not backed by any file; its contents are initial‐
> ized to zero.  The fd and offset arguments are ignored; however,
> some implementations require fd to be -1  if MAP_ANONYMOUS  (or
> MAP_ANON)  is specified, and portable applications should ensure
> this.  The use of MAP_ANONYMOUS in conjunction  with MAP_SHARED
> is only supported on Linux since kernel 2.4.
> ----------
>
> what are you missing from this ?

My linux mmap manpage says:
---------------------------
       MAP_ANONYMOUS
              The  mapping  is not backed by any file; the fd and offset argu-
              ments are ignored.  The use of this  flag  in  conjunction  with
              MAP_SHARED is only supported on Linux since kernel 2.4.

       MAP_ANON
              Alias for MAP_ANONYMOUS.  Deprecated.
---------------------------

My bsd mmap manpage says:
-------------------------------
     MAP_ANON            Map anonymous memory not associated with any specific
                         file.  The file descriptor is not used for creating
                         MAP_ANON regions, and must be specified as -1.  The
                         mapped memory will be zero filled.
-------------------------------


Christoph


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