>>> On 13.06.17 at 18:20, <andrew.coop...@citrix.com> wrote:
> 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.gr...@arm.com>
>> ---
>> Cc: Andrew Cooper <andrew.coop...@citrix.com>
>> Cc: George Dunlap <george.dun...@eu.citrix.com>
>> Cc: Ian Jackson <ian.jack...@eu.citrix.com>
>> Cc: Jan Beulich <jbeul...@suse.com>
>> Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
>> Cc: Stefano Stabellini <sstabell...@kernel.org>
>> Cc: Tim Deegan <t...@xen.org>
>> Cc: Wei Liu <wei.l...@citrix.com>
>>
>> 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.
Except that you can't put a #define in a macro definition, and producing
a static const wouldn't help Julien's case of wanting it in the initializer of
a static variable. So best I can come up with right now would be to
introduce a separate
#define TYPE_SAFE_CONSTANT(name, val) \
(name##_t){ val }
and
#define TYPE_SAFE_CONSTANT(name, val) \
(name##_t)(val)
for the !NDEBUG / NDEBUG cases respectively and use it as
#define INVALID_MFN TYPE_SAFE_CONSTANT(mfn, ~0UL)
Jan
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