bizarre em + TSO + MSS issue in RELENG_7

Pyun YongHyeon pyunyh at gmail.com
Sat Nov 17 22:06:45 PST 2007


On Sat, Nov 17, 2007 at 10:00:16PM -0800, Jack Vogel wrote:

[...]
 > >
 > > It seems that em_tso_setup() doesn't clear txd_upper/txd_lower in
 > > failure path so that unintialized value could be used in subsequent
 > > Tx descriptor setup.
 > > How about clearing those variable?(Patch attached)
 > >
 > > It seems that em(4) uses EM_TSO_SIZE(64K) to create DMA tag. A packet
 > > can have 64K payload under TSO so its the mximum size of the mbuf
 > > chain would be 64K + sizeof(link layer). So I guess the EM_TSO_SIZE
 > > should be increased to hold sizeof(link layer).
 > > It had been a long time since I looked into em(4) so I'm not sure.
 > 
 > Huh? They are set to 0 on entry, and not touched again before you go
 > into the setup routine, your change has no effect.
 > 

Sorry for the noise.

-- 
Regards,
Pyun YongHyeon


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