svn commit: r263957 - in head/sys: dev/age dev/alc dev/ale dev/bce dev/bge dev/fxp dev/jme dev/msk dev/nfe dev/sge pci

[Yonghyeon PYUN]

On Sun, Mar 30, 2014 at 09:00:59PM -0700, John-Mark Gurney wrote:
> Pyun YongHyeon wrote this message on Mon, Mar 31, 2014 at 01:54 +0000:
> > Author: yongari
> > Date: Mon Mar 31 01:54:59 2014
> > New Revision: 263957
> > URL: http://svnweb.freebsd.org/changeset/base/263957
> > 
> > Log:
> >   Increase the number of TX DMA segments from 32 to 35.  It turned
> >   out 32 is not enough to support a full sized TSO packet.
> >   While I'm here fix a long standing bug introduced in r169632 in
> >   bce(4) where it didn't include L2 header length of TSO packet in
> >   the maximum DMA segment size calculation.
> 
> I assume all of the hardware supports this increase?
> 

Yes.  Data sheet does not mention about such limitation.  txp(4)
has a limitation on the number of TX segments but I didn't
implement TSO in txp(4).

> Also, is there a reason to only increase up to 35 and not something
> larger, like 64?  Is there a memory or performance penalty?
> 

If 64 does not overflow kernel stack we can also bump the number to
64.