PERFORCE change 111230 for review

[Ruslan Ermilov]

On Thu, Dec 07, 2006 at 04:16:41PM +0000, Robert Watson wrote:
> On Thu, 7 Dec 2006, Paolo Pisati wrote:
> 
> >Then, after a discussion on irc, pull the plug on any present (and future) 
> >hackery & half-baked solution, and declare in kernel libalias incompatible 
> >with tso.
> 
> This seems silly -- why is it not compatible?  Perhaps I misunderstand, but 
> I thought TSO passed down valid TCP/IP packets, they just happen to be 
> really long, and will be post-processed by the hardware into a series of 
> shorter segments with the same header properties.  Imagine the ethernet 
> device as a "router" that's performing TCP fragmentation for you, rather 
> than IP fragmentation.
> 
It's a limitation of the current libalias code which grew
up on top of userland version -- it doesn't currently know
how to traverse mbufs, and instead requires a contiguous
piece of (packet) data to do its job.

: #ifdef _KERNEL
: /*
:  * m_megapullup() function is a big hack (only used in ng_nat and ipfw+nat).
:  *
:  * It allocates an mbuf with cluster and copies the whole
:  * chain into cluster, so that it is all contigous and the
:  * whole packet can be accessed via char pointer.
:  * This is required, because libalias doesn't have idea
:  * about mbufs.
:  * 
:  * On success, m_megapullup returns an mbuf with cluster
:  * containing the input packet, on failure NULL.
:  * In both cases, the input packet is consumed.
:  */


Cheers,
-- 
Ruslan Ermilov
ru at FreeBSD.org
FreeBSD committer
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