ARM network trouble after recent mbuf changes

[Warner Losh]

On Aug 27, 2013, at 12:53 AM, Andre Oppermann wrote:

> On 27.08.2013 00:22, Thomas Skibo wrote:
>> On 8/26/13 2:11 PM, Andre Oppermann wrote:
>>> 
>>> Can you try this patch see check if it makes a difference on the bitfield?
>> 
>> Actually, this works for me.  But, I'm worried that somewhere else something is going to trip over a
>> struct pkthdr not being 64-bit aligned.  There are several 64-bit fields in there.
> 
> The problem is the disconnect between the definition of MLEN and MHLEN and
> the effective size/padding of struct mbuf.  That's the true bug.
> 
> On LP64 all is fine.  On i386 it turns out to be fine too because doesn't
> care.
> 
> MLEN and MHLEN are incorrectly derived.  In fact they should be derived from
> stuct mbuf where this padding would be taking into account.  However the way
> it is structured right now it that would create a circular dependency.
> 
> Please try the patch below to confirm.  If it fixes your problem for now
> I'm going to commit as an immediate fix while searching for a better long
> term stable solution.
> 
> -- 
> Andre
> 
> Index: sys/mbuf.h
> ===================================================================
> --- sys/mbuf.h  (revision 254953)
> +++ sys/mbuf.h  (working copy)
> @@ -94,6 +94,9 @@
>        int32_t          mh_len;        /* amount of data in this mbuf */
>        uint32_t         mh_type:8,     /* type of data in this mbuf */
>                         mh_flags:24;   /* flags; see below */
> +#if defined(__ILP32__)
> +       uint32_t         mh_pad;        /* pad to 64 bit alignment */
> +#endif
> };
> 
> /*

There should be a CTASSERT() here to make sure there's no mismatch...

Warner