Hello Dima,
On 6/16/26 18:20, Ruinskiy, Dima wrote:
On 15/06/2026 23:36, Helge Deller wrote:
On 6/15/26 18:41, Andrew Lunn wrote:
On Sun, Jun 14, 2026 at 11:48:08PM +0200, Helge Deller wrote:
I'm regularily facing the known "eno1: Detected Hardware Unit Hang:"
with my on-board intel e1000e NIC hardware.
Since none of he various tips on the internet helped, I had the idea
to setup a master/slave bond networking to fail over to another NIC when
the Intel chip hangs.
Sadly this doesn't work as intended, because the link of the intel NIC
isn't reported "down", so the failover never happens, unless I manually
start "ifconfig eno1 down".
My question: Shouldn't the intel NIC ideally report Link Down if we know
it hangs? That way a fail-over should at least happen, right?
Below is a completely untested patch.
Does it make sense that I try to test and/or develop such a patch, or
are there things I miss?
If the interface is dead, then setting the carrier down makes a lot of
sense.
That's what I think as well. Thanks for confirming.
One question i have is, what do you need to do to recover the
hardware? Will it correctly set the carrier up when you do the
recovery?
The only way I could recover was to plug the network cable and re-insert it.
I have not tested bringing the NIC down.
But in both cases the driver will need to re-detect the media & link
Also, just looking at your proposed change, it is not clear to me why
such an assignment will result in carrier down. It would be good to
explain it in the commit message.
Sure. The patch I attached was completely untested and just based on
the analysis of the flow and how to make the Link possibly report to be down.
Maybe someone knowledgeable of the driver has a better suggestion how to
report the link down situation in a clean way?
Helge
This does not seem like the right direction to me.
The "Detected Hardware Unit Hang" print does not indicate that the
interface is dead, but that the transmitter is stalled.
Ok. But effectively it means there can nothing be transmitted then at this
stage,
which somehow is the same as if the Link would be down.
This can be due to an unusually high load, or a HW fault / race condition with
another component, etc.
When a hang is detected, the transmitter is stopped with
netif_stop_queue() and eventually ndo_tx_timeout triggers a full
reset to the device, which in many cases recovers it from the hang.
That would be optimal, but I have never seen it recovering from such stalls
since years.
Also looking at the many reports in the internet, people say it just
hangs and does not recover until the cable is plugged out (I might be wrong!).
If the hang is persistent, we try to understand the cause and debug
it. Permanently marking the device as 'down' because it hung once is
not going to be the optimal solution.
Of course debugging this situation is preferred but it does not help when
the productive remote system stays unreachable forever.
Right now it just fills the syslog with the same stuck message.
Even an module option like "report_link_down_on_hang after 5 automatic re-tries"
would be good compromise.... You still should be able to get the necessary
debug info then.
Helge
