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Problem with ibm_emac driver

DISCUSSION Ian Remmler 2 participants 2 messages Jul 20, 2006

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Hi,

I'm having a problem with the ibm_emac driver for the built in gigabit ethernet on the 440gx. I was hoping someone could shed some light or at least point me in the right direction.

I'm using a GMS P502 board runing 2.4.27-pre3 (from GMS). The problem we are having is this: when we push data over the emac interface (eth0 and eth1 both show the problem), we sporadically get a "MAL: Rx descriptor error..." from mal_rxde in ibm_ocp_mal.c.

Occasionally, the interface will "freeze up" for a few seconds. An ifconfig down/up will bring it back, but from then on it will freeze up again right away.

It looks to me like this error indicates that we're out of RX buffers, but I don't how we would be running out. I'm no kernel or networking expert, but I thought the TCP stack would take care of throttling itself to prevent that sort of thing. I would appreciate any help.

Thanks,
- Ian.

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#1 lore raw
Quoted 16 lines · Ian Remmler

Hi,

I'm having a problem with the ibm_emac driver for the built in gigabit ethernet on the 440gx. I was hoping someone could shed some light or at least point me in the right direction.

I'm using a GMS P502 board runing 2.4.27-pre3 (from GMS). The problem we are having is this: when we push data over the emac interface (eth0 and eth1 both show the problem), we sporadically get a "MAL: Rx descriptor error..." from mal_rxde in ibm_ocp_mal.c.

Occasionally, the interface will "freeze up" for a few seconds. An ifconfig down/up will bring it back, but from then on it will freeze up again right away.

Quoted 5 lines

It looks to me like this error indicates that we're out of RX buffers, but I don't how we would be running out. I'm no kernel or networking expert, but I thought the TCP stack would take care of throttling itself to prevent that sort of thing. I would appreciate any help.

No idea what GMS is, but they seem to use old buggy EMAC driver.

You can use kernel.org's 2.6 or 2.4.31 backport at
http://kernel.ebshome.net/

As a side note, TCP cannot throttle _all_ Rx traffic, think for example of a fast box sending a lot of small UDP packets to the 440gx.

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