Re: [E1000-devel] Tx interrupt during DMA

[Tamas B. <tb...@mi...>]

Feldman, Scott schrieb:
>>Is it admissible for the transmit interrupt to
>>arrive during an ongoing DMA, or is it a malfunction
>>of my system?
>=20
>=20
> How do you know it's a transmit interrupt?  Rx and Tx events will
> generate interrupts.  The 8254x controller could be fetching Rx or Tx
> descriptors, or fetching Tx buffers.  Do you know what data is being
> DMA'ed? =20
>=20
> -scott
>=20

I have cross-linked my 82540 controller with a broadcom
gigabit card. I don=B4t send packets from the broadcom
controller, just transmit ethernet frames with sendto()
from the 82540. It=B4s either a Tx descriptor or Tx buffer
that is DMA'ed when the interrupt arrives.

Check out the screenshot I made on the scope when the
crash occured. Channel 1 is the PCI_REQ# signal and
channel 2 the PCI_INT#, both coming from the 82540.

The card goes crazy when the interrupt comes during DMA.

- tamas