From: Stefan Sperling <stsp@stsp.name>
Subject: Re: bge/bnx/iavf/igc/ix/ixl/ngbe/pcn: ifq_restart() fix
To: Dmitry Bogdan <dmitry.bogdan@gmail.com>
Cc: tech@openbsd.org
Date: Fri, 27 Jun 2025 13:53:00 +0200

On Thu, Jun 26, 2025 at 10:57:41PM +0300, Dmitry Bogdan wrote:
> Hi Stephan and tech@
> I have such a great NIC as AMD Lance FastEthernet (and another one, much
> more ancient 10mbit with RJ-45 and AUI interface).
> 
> > pcn0 at pci4 dev 6 function 0 "AMD 79c970 PCnet-PCI" rev 0x25, Am79c971,
> rev 5: apic 24 int 21, address 00:60:b0:eb:73:c5
> > lxtphy0 at pcn0 phy 1: LXT970, rev. 0
> > ukphy0 at pcn0 phy 31: Generic IEEE 802.3u media interface, rev. 1: OUI
> 0x00001a, model 0x0001
> 
> I can not manage the interface to get stuck forever. Yes, when I run a
> thing such as
> 
> > iperf -u -l0 -t0 -c ${serveraddr}
> 
> I see a tons of qdrops in kstat:
> 
> >pcn0:0:txq:0
> >         packets: 36982186 packets
> >           bytes: 1675836505 bytes
> >          qdrops: 48256453 packets
> >          errors: 0 packets
> >            qlen: 0 packets
> >         maxqlen: 511 packets
> >         oactive: false
> >        oactives: 4607637
> 
> and oactivee is set to true.
> Also I can see ping drops (no buffer space avail) and delays.
> 
> But when I stop the iperf client everything is going just fine. oactive in
> kstat becomes false again. Pings are ok, browser works fine.
> 
> Tested with 7.7 syspatch from 04 may AND with -current kernel + old 7.7
> user space + you modifications with done variable in pcn_txintr func.
> Behavior is the same in both cases.

Thanks for testing! So it seems no fix is needed for pcn(4) after all.