On Thursday 24 February 2005 12:46, zDL Linux PPC wrote: > I have been doing some experiments with Jumbo packets (MTU 9000) and have > noticed that once you exceed the 2KB fifo size, I end up with no response > from the box. > > I can ping the box with no problem at all at sizes greater than 2KB, however > upon further investigation I noticed packets of size 2006 bytes causes no > further packet to be transmitted (adding debug prints to ibm_emac_core.c, > the driver believes the packet has been transmitted), after adding a further > 42 bytes of header information this comes to the exact size of the Transmit > Fifo 2048 (2KB). I have also changed the Transmit Fifo Register to 1024 > bytes, this solves the problem at 2006 bytes however now it has moved to 982 > bytes of data (+42bytes of header = 1024) > > Has anyone else experienced this problem while either using a smaller > transmit fifo (512 or 1024 bytes) and MTU 1500 or a larger MTU (>2033) and > EMAC transmit fifo of 2048. I guess this will really apply to people with > larger MTU not many will decrease the Tx fifo, and I am further guessing > that not many are using 9000 MTU as not much hardware seems to support it, I > can only use it through a direct connection between PC's and not through a > switch! > > Any suggestions on how to overcome this problem??? My only idea is to either > add data to the packet (don't think this will work) or forceably fragment > the packet (if it is 2K in size) to ensure that it never uses the exact size > of the tx fifo.....
Have you applied Matt Porters patch? It has been submitted at the beginning of this month? Gerhard -- Gerhard Jaeger <gjaeger at sysgo.com> SYSGO AG Embedded and Real-Time Software www.sysgo.com | www.elinos.com | www.pikeos.com | www.osek.de
