From: Yuval Mintz <yuval.mi...@qlogic.com>
Date: Tue, 10 May 2016 18:15:08 +0000
>> > I'm not entirely convinced this is true; If we'll not enforce the
>> > alignment of this 64-bit field, it's possible there will be
>> > differences between 32-bit and 64-bit machines versions of this struct.
>> > You have to recall that this is going to be copied via DMA between PF
>> > and VF, so they must have the exact same representation of the structure.
>>
>> Then use properly sized types to fill in all the space in the structure,
>> that's how
>> you guarantee layout, not aligned_u64. Also, do not use the packed
>> attribute.
>>
>> struct foo {
>> u32 x;
>> u32 y;
>> u64 z;
>> };
>>
>> 'z' will always be 64-bit aligned.
>
> Perhaps my bit-numeric is a bit weak - why is it so?
foo is 64-bit aligned, therefore a properly aligned struct member will
be so as well.
We absolutely depend upon this for several data structures in the kernel.
