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Re: 2.4.21: bug report for tg3: tx lockup when changing MTU

To: Jeff Garzik <jgarzik@xxxxxxxxx>
Subject: Re: 2.4.21: bug report for tg3: tx lockup when changing MTU
From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Date: Fri, 01 Aug 2003 17:24:00 -0700
Cc: "'netdev@xxxxxxxxxxx'" <netdev@xxxxxxxxxxx>
In-reply-to: <3F2AFE7A.10203@xxxxxxxxx>
Organization: Candela Technologies
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Jeff Garzik wrote:
Ben Greear wrote:

I just noticed that if you change the MTU of a tg3 NIC, it will not work
untill you ifdown/ifup it. This problem is repeatable on tg3, and does not
happen with the e1000 driver/cards.

I am setting the MTU via an ioctl call, not via ifconfig or something like

Can you provide the ioctl call info, so I can reproduce?

And, are you changing MTU when the interface is up or down?

Interface is up and transmitting/receiving pkts at the time.

I just reproduced it with commands below.  It is probably a race,
so not sure that either of these will always fail.  Running about
10kpps rx+tx.  Was sending pktgen (UDP) traffic of fixed length, so the actual
transmitted packet sizes remains the same in this case.

# MTU is at 1500
ifconfig eth5 mtu 4096  #worked
ifconfig eth5 mtu 4000  # failed.

Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc

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