On Thu, Sep 5, 2013 at 11:17 AM, David Miller <da...@davemloft.net> wrote: > From: Jesse Gross <je...@nicira.com> > Date: Thu, 5 Sep 2013 10:41:27 -0700 > >> -} __aligned(__alignof__(long)); >> +} __aligned(8); /* 8 byte alignment ensures this can be accessed as a long >> */ > > This kind of stuff drives me crazy. > > If the issue is the type, therefore at least use an expression that > mentions the type explicitly. And mention the actual type that > matters. "long" isn't it.
'long' actually is the real type here. When doing comparisons, this structure is being accessed as a byte array in 'long' sized chunks, not by its members. Therefore, the compiler's alignment does not necessarily correspond to anything for this purpose. It could be a struct full of u16's and we would still want to access it in chunks of 'long'. To completely honest, I think the correct alignment should be sizeof(long) because I know that 'long' is not always 8 bytes on all architectures. However, you made the point before that this could break the alignment of the 64-bit values on architectures where 'long' is 32 bits wide, so 8 bytes is the generic solution. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
