On 14.12.2016 19:06, Jason A. Donenfeld wrote:
> Hi David,
>
> On Wed, Dec 14, 2016 at 6:56 PM, David Miller <davem@xxxxxxxxxxxxx> wrote:
>> Just marking the structure __packed, whether necessary or not, makes
>> the compiler assume that the members are not aligned and causes
>> byte-by-byte accesses to be performed for words.
>> Never, _ever_, use __packed unless absolutely necessary, it pessimizes
>> the code on cpus that require proper alignment of types.
>
> Oh, jimminy cricket, I did not realize that it made assignments
> byte-by-byte *always*. So what options am I left with? What
> immediately comes to mind are:
>
> 1)
>
> struct {
> u64 a;
> u32 b;
> u32 c;
> u16 d;
> u8 end[];
I don't think this helps. Did you test it? I don't see reason why
padding could be left out between `d' and `end' because of the flexible
array member?
Bye,
Hannes
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