cvs commit: src/sys/net if_bridge.c

[Andrew Thompson]

On Fri, Aug 12, 2005 at 12:32:27AM +0200, Max Laier wrote:
> On Thursday 11 August 2005 22:57, Andrew Thompson wrote:
> > thompsa     2005-08-11 20:57:59 UTC
> >
> >   FreeBSD src repository
> >
> >   Modified files:        (Branch: RELENG_6)
> >     sys/net              if_bridge.c
> >   Log:
> >   MFC: if_bridge.c, r.1.5
> >
> >   > Use m_copypacket() which is an optimization of the common case
> >   > m_copym(m, 0, M_COPYALL, how).
> >   >
> >   > This is required for strict alignment architectures where we align the
> >   > IP header in the input path but m_copym() will create an unaligned copy
> >   > in bridge_broadcast(). m_copypacket() preserves alignment of the first
> >   > mbuf.
> 
> I guess we should document this difference between m_copym and m_copypacket ?!
> 

It is in the comment block which is how I discovered it, but mbuf(9) is missing
the info about alignment.

uipc_mbuf.c:
 /*
  * Copy an entire packet, including header (which must be present).
  * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
  * Note that the copy is read-only, because clusters are not copied,
  * only their reference counts are incremented.
  * Preserve alignment of the first mbuf so if the creator has left
  * some room at the beginning (e.g. for inserting protocol headers)
  * the copies still have the room available.
  */
 struct mbuf *
 m_copypacket(struct mbuf *m, int how)