kern/42323: tso4 problem

[6bone%6bone.informatik.uni-leipzig.de@localhost]

>Number:         42323
>Category:       kern
>Synopsis:       tso4 problem
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Nov 15 16:15:00 +0000 2009
>Originator:     Uwe Toenjes
>Release:        NetBSD 5.0_STABLE
>Organization:
University of Leipzig
>Environment:
NetBSD 6bone.informatik.uni-leipzig.de 5.0_STABLE NetBSD 5.0_STABLE (MYCONF) 
#2: Mon Nov  9 16:17:44 CET 2009  
root%6bone.informatik.uni-leipzig.de@localhost:/usr/obj/sys/arch/amd64/compile/MYCONF
 amd64
>Description:
if tso4 is enabled on my Intel NIC the server sometimes loses its network 
connection and dmesg reports

wm0: device timeout (txfree 3854 txsfree 0 txnext 4042)
wm0: device timeout (txfree 3842 txsfree 0 txnext 301)
wm0: device timeout (txfree 3826 txsfree 0 txnext 3210)

the switch reports link down/up events.
the same problem occurs with the current kernel.
>How-To-Repeat:
use tso4 at intel NICs with the following chipset:

wm0 at pci9 dev 0 function 0: Intel PRO/1000 PT (82571EB), rev. 6
wm0: interrupting at ioapic0 pin 16
wm0: PCI-Express bus
wm0: 65536 word (16 address bits) SPI EEPROM
wm0: Ethernet address 00:15:17:0e:98:5e

>Fix: