Re: [Xen-devel] [PATCH 01/24] xen/mm: Don't use _{g, m}fn for defining INVALID_{G, M}FN

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/06/17 17:13, Julien Grall wrote:
> INVALID_{G,M}FN are defined using static inline helpers _{g,m}fn.
> This means, they cannot be used to initialize a build time static variable:
>
> In file included from mm.c:24:0:
> xen/xen/include/xen/mm.h:59:26: error: initializer element is not constant
>  #define INVALID_MFN      _mfn(~0UL)
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> ---
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
>
> I know that this solution will not work for non-debug build. I would
> like input from the community on way to fix it nicely.

Hmm - a proper typedef gets inserted.  I presume the compiler objects to
(unsigned long){ ~0UL } to initialise a scalar?

It might be better to move the definition of INVALID_$FOO into the
TYPE_SAFE() declaration so we can create an appropriate initialiser for
each both builds.

~Andrew

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