Re: [-next] openvswitch BUILD_BUG_ON failed

[David Miller <davem@davemloft.net>]

From: Jesse Gross <jesse@nicira.com>
Date: Thu, 29 Aug 2013 14:42:22 -0700

> On Thu, Aug 29, 2013 at 2:21 PM, Geert Uytterhoeven
> <geert@linux-m68k.org> wrote:
>> However, I have some doubts about other alignment "enforcements":
>>
>> "__aligned(__alignof__(long))" makes the whole struct aligned to the
>> alignment rule for "long":
>>    1. This is only 2 bytes on m68k, i.e. != sizeof(long).
>>    2. This is 4 bytes on many 32-bit platforms, which may be less than the
>>       default alignment for "__be64" (cfr. some members of struct
>>       ovs_key_ipv4_tunnel), so this may make those 64-bit members unaligned.
> 
> Do any of those 32-bit architectures actually care about alignment of
> 64 bit values? On 32-bit x86, a long is 32 bits but the alignment
> requirement of __be64 is also 32 bit.

All except x86-32 do, it is in fact the odd man out with respect to this
issue.