kern/52068: i386 wmX (i82574L) xmit checksum offloading broken

[kardel%netbsd.org@localhost]

>Number:         52068
>Category:       kern
>Synopsis:       i386 wmX (i82574L) xmit checksum offloading broken
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Mar 14 07:35:00 +0000 2017
>Originator:     kardel%netbsd.org@localhost
>Release:        NetBSD 7.99.65
>Organization:
	
>Environment:
	
	
System: NetBSD Gateway 7.99.65 NetBSD 7.99.65 (GATEWAY) #8: Sun Mar 12 10:14:06 CET 2017 kardel@xxx:/fs/raid2a/src/NetBSD/cur/src/obj.i386/sys/arch/i386/compile/GATEWAY i386
Architecture: i386
Machine: i386
>Description:
	With hw checksum offloading in send path enabled (ip4csum, udp4csum, tcp4csum) packets with wrong checksums arrive at other systems causing packet drops.
	Symptoms disappear when disabling at least pat of the offloading (e. g. ip4csum or udp4csum).
	For udp csum error ip4csum and udp4csum is required. Same goes for ip4csum and tcp4csum.
	This is a regression from 7.99.16 or later.

	dmesg information:
	wm0 at pci5 dev 0 function 0: Intel i82574L (rev. 0x00)
	wm0: for TX and RX interrupting at msix0 vec 0 affinity to 0
	wm0: for TX and RX interrupting at msix0 vec 1 affinity to 1
	wm0: for LINK interrupting at msix0 vec 2
	wm0: PCI-Express bus
	wm0: 2048 words (8 address bits) SPI EEPROM, version 2.1.2, Image Unique ID 0000ffff
	wm0: Ethernet address 00:00:24:d1:5e:ec
	makphy0 at wm0 phy 1: Marvell 88E1149 Gigabit PHY, rev. 1

>How-To-Repeat:
	Pick a recent -current like 20170312. a Soekris 6501 (i82574L), i386 arch and start watching csum errors on other system communicating 
	with the Soekris. Issues go away when you turn off hw csum offload (either one of ip4csum or udp4csum for udp or one of ip4csum or tcp4csum).

>Fix:
	workaround: disable any hw checksum offload in the send path

>Unformatted: