em driver problem (system lock)

[Fabien THOMAS]

      Hi,

We use a lot of intel gigabit card and since the first
time we use it we experience some strange hard lock of the system
(4.9|FreeBSD-stable). We have tried several driver version (it is not
related to a version). We use the card in polling mode but it seems that
the problem can be fired even in interrupt mode.

What i found during the debugging on a fiber card:

1) original driver did not lock but when the other end is rebooted i've
around 10 linkup/linkdown

2) removing linkup/linkdown printf: driver lock each time the other end
system is rebooted!

3) removing the E1000_IMC_RXSEQ in disable_intr correct the lock but i
do not understand why:
      a) E1000_IMC_RXSEQ need to be left when disabling intr?
      b) the system completly lock (even under debugger) for just an
interrupt source enabled?

static void
em_disable_intr(struct adapter *adapter)
{
      E1000_WRITE_REG(&adapter->hw, IMC,
              (0xffffffff));/* & ~E1000_IMC_RXSEQ));*/
      return;
}

What do you think of that ?

fabien

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