Forcedeth and jumbo frames

mattross · 23 Aug 2008 at 17:01

I have kernel 2.6.26 compiled from source. My network card is an onboard Nforce NIC using the Forcedeth 0.61 driver. It is running at gigabit speed but I would like to enable jumbo frames support.

I have tried 'ifconfig eth0 mtu 7000', my other PC only supports up to this, and it gives error 'SIOCSIFMTU: Invalid argument'. Running 'ip route get 192.168.1.100' tells me the MTU is 1500.

I can't find any clear information either way to tell me if this should work or not. Has anyone else managed to get jumbo frames working with this driver?

mattross · 24 Aug 2008 at 12:27

It seems whatever value I try and set I get that error. I don't know if the Forcedeth driver in kernel 2.6.26 has been patched for jumbo frame support and I can't find the patch anywhere so I can download it and see if it is in the forcedeth.c in 2.6.26.

mattross · 24 Aug 2008 at 15:59

Yeah I found that in mine. Maybe my card doesn't support it? Here are the details:

Code:

00:14.0 Bridge: nVidia Corporation MCP51 Ethernet Controller (rev a1)
        Subsystem: Foxconn International, Inc. Device 0d00
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
        Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0 (250ns min, 5000ns max)
        Interrupt: pin A routed to IRQ 23
        Region 0: Memory at fe02b000 (32-bit, non-prefetchable) [size=4K]
        Region 1: I/O ports at c800 [size=8]
        Capabilities: [44] Power Management version 2
                Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold+)
                Status: D0 PME-Enable+ DSel=0 DScale=0 PME-
        Kernel driver in use: forcedeth

mattross · 24 Aug 2008 at 16:24

OK well I can live with that. I could always buy a separate card. Currently getting about 43MB/s so it's not the end of the world.

Thanks for your help.

mattross · 24 Aug 2008 at 20:30

Thanks I'll give it a go in the next day or two and post back, if the card hasn't exploded in my face

mattross · 30 Aug 2008 at 12:53

Got round to trying the patch. It let me set the MTU size to anything up to 9000 bytes but when transferring a large file it would kill the network connection within about thirty seconds. After a reboot I looked at the syslog and found this:

Code:

Aug 30 12:39:13 kaz kernel: NETDEV WATCHDOG: eth0: transmit timed out
Aug 30 12:39:13 kaz kernel: eth0: Got tx_timeout. irq: 00000000
Aug 30 12:39:13 kaz kernel: eth0: Ring at 7dc74000
Aug 30 12:39:13 kaz kernel: eth0: Dumping tx registers
[massive data dump]
Aug 30 12:39:13 kaz kernel: eth0: tx_timeout: dead entries!

The transfer, while it lasted, was about 1-2MB/s slower anyway.

Was worth trying but at least I now know for sure the MCP51 does not support jumbo frames.

Thanks.