On 27/06/2017 10:46, Tim Deegan wrote:
At 10:33 +0100 on 27 Jun (1498559600), Julien Grall wrote:The current implementation of {G,M}FN_INVALID cannot be used to initialize global variable because the initializer element is not a constant. Due to a bug in GCC 4.9 and older ([1]), it is not easy to find a common value to initialize a variable and directly passed as an argument. Introduce 2 news define {G,M}FN_INVALID_INITIALIZER to be used for initializing a variable. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64856 Signed-off-by: Julien Grall <julien.gr...@arm.com>Acked-by: Tim Deegan <t...@xen.org> (and Ack for the revert too) but please choose either { ~0UL } or {~0UL} and use it for both.
Whoops. Sorry for that. I will stick to {~0UL} unless someone prefer the { ~0UL }.
Cheers,
--- Build tested it with: * ARM: GCC 4.9.4, 5.1, 4.3, 6.1.1, 7.1.0 * x86: Clang 3.5.0, 3.6.0, 3.6.2, 3.8.0, 3.9.0, 4.0.0 With introducing a dummy global variable common/mm.c: mfn_t foo = INVALID_MFN_INITIALIZER --- xen/include/xen/mm.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h index 0050fba498..251db4ffa1 100644 --- a/xen/include/xen/mm.h +++ b/xen/include/xen/mm.h @@ -57,6 +57,11 @@ TYPE_SAFE(unsigned long, mfn); #define PRI_mfn "05lx" #define INVALID_MFN _mfn(~0UL) +/* + * To be used for global variable initialization. This workaround a bug + * in GCC < 5.0. + */ +#define INVALID_MFN_INITIALIZER {~0UL} #ifndef mfn_t #define mfn_t /* Grep fodder: mfn_t, _mfn() and mfn_x() are defined above */ @@ -90,6 +95,11 @@ static inline bool_t mfn_eq(mfn_t x, mfn_t y) TYPE_SAFE(unsigned long, gfn); #define PRI_gfn "05lx" #define INVALID_GFN _gfn(~0UL) +/* + * To be used for global variable initialization. This workaround a bug + * in GCC < 5.0 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64856 + */ +#define INVALID_GFN_INITIALIZER { ~0UL } #ifndef gfn_t #define gfn_t /* Grep fodder: gfn_t, _gfn() and gfn_x() are defined above */ -- 2.11.0
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