From: Mika Westerberg <mika.westerb...@linux.intel.com>
Date: Wed, 27 Sep 2017 14:32:41 +0300
> Just for my education, is there some rule which tells when __packed is
> to be used? For example the above structures are all 32-bit aligned but
> how about something like:
>
> struct foo {
> u32 value1;
> u8 value2;
> };
>
> If the on-wire format requires such structures I assume __packed
> is needed here?
Usually header elements are 32-bit aligned in a protocol, so it wouldn't
be specified like that.
The only legitimate case I've seen is where things are purposefully
misaligned within the header, like this:
struct foo {
u16 x;
u64 y;
u16 z;
};
Where the 'y' element is 2-byte aligned.
Fortunately, those situations are extremely rare.
