Re: via-rhine v1.05: Oversized Ethernet frames when in promisc mode

From: Urban Widmark (urban@svenskatest.se)
Date: Fri Jun 09 2000 - 17:37:45 EST


On Fri, 9 Jun 2000, Alan Cox wrote:

> Just a random pondering - the only other way I can see short frames occuring
> is if the card is managing to receive a frame into a buffer that is still
> being set up again after use ?

I don't see how ... :(

The descriptors are protected by a ownership flag, when 1 the driver owns
it, when 0 the driver owns it. If you don't own it, you don't touch it. I
could be wrong, my english isn't good enough to decipher this:

  "Owner : This bit control by driver, 1 to identify this descriptor own
   by VT86C100A controller, 0 means this descriptor be a free
   descriptor; Driver must set this bit be zero when initialed."
(free?)

The driver only sets it to 1 after setting it up (allocating a fresh skb
and such). The card (I assume) sets it to 0 after having received into it
and then raises the interrupt. The driver only looks at the ones with
ownership=0.

There is someone else that reported problems with IP masquerading
(possibly with packet filter?) and the via-rhine (different error message
and not related to sniffing). Here it was a packet-filtering firewall
(with ip-masq?) ...

IP masq is working fine here, I have flood pings, ftp downloads, tcpdump
(on the internal via interface).

/Urban

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