splitting m_flags to pkthdr.flags + m_flags

[Gleb Smirnoff]

On Fri, Nov 02, 2012 at 01:54:50PM +0100, Andre Oppermann wrote:
A> > An attentive reader may have noticed that I missed M_NOFREE and M_FREELIST.
A> > Yep, these flags coming from historical mbuf allocator from FreeBSD 4.x times
A> > are about to be deleted, we carefully examine them, but never set. Patch
A> > for review attached.
A> 
A> Looks good.  Go ahead from me.

History review reveals that M_NOFREE comes from r172463 by Kip Macy.
The idea was to have mbufs embdedded into clusters. The feature isn't
used by any module and isn't tested at all.

I ponder on should we leave the code as is or not?

M_FREELIST actually has nothing to do with historic mbuf allocator. It
was a bandaid that helped to debug double-frees. The code was washed
out from the repo, only the flag left. Also the functionality is now
available via generic allocator invariants. So M_FREELIST definitely
should be deleted.

But I'm not sure about M_NOFREE.

-- 
Totus tuus, Glebius.