xl0: transmission error: 90

[Ulrik Guenther]

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Hi everyone,

on my 5.4-RC1 installation with a 3com 3c905B NIC I got the following
messages while transferring a big file (31GByte) over 100MBit ethernet:

Apr 15 08:46:18 verleihnix kernel: xl0: transmission error: 90
Apr 15 08:46:18 verleihnix kernel: xl0: tx underrun, increasing tx start
threshold to 120 bytes
Apr 15 08:46:18 verleihnix kernel: xl0: transmission error: 90
Apr 15 08:46:18 verleihnix kernel: xl0: tx underrun, increasing tx start
threshold to 180 bytes
Apr 15 08:46:19 verleihnix kernel: xl0: transmission error: 90
Apr 15 08:46:19 verleihnix kernel: xl0: tx underrun, increasing tx start
threshold to 240 bytes
Apr 15 08:46:19 verleihnix kernel: xl0: transmission error: 90
Apr 15 08:46:19 verleihnix kernel: xl0: tx underrun, increasing tx start
threshold to 300 bytes
Apr 15 08:46:21 verleihnix kernel: xl0: transmission error: 90
Apr 15 08:46:21 verleihnix kernel: xl0: tx underrun, increasing tx start
threshold to 360 bytes
Apr 15 08:47:29 verleihnix kernel: xl0: transmission error: 90
Apr 15 08:47:29 verleihnix kernel: xl0: tx underrun, increasing tx start
threshold to 420 bytes

So, okay the threshold was increaed in 60byte steps from 120 to 420
bytes, then it stopped. This procedure took place only during the first
gigabytes of the transmission. I noticed no negative side effects (say:
the file arrived completely on the other computer, checksum was okay as
well). Transmission was done via SSH/SCP.

Now my question: What do these messages from the xl(4) mean?

Thanks in advance,

Ulrik Guenther
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