Bug 43277

Summary:	net/e1000e set mtu larger than 1500 fails
Product:	Networking	Reporter:	Christer Ekholm (che)
Component:	IPV4	Assignee:	Stephen Hemminger (stephen)
Status:	RESOLVED INVALID
Severity:	normal
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	3.4	Subsystem:
Regression:	Yes	Bisected commit-id:

Description Christer Ekholm 2012-05-22 18:13:21 UTC

In kernel 3.4 I can no longer use jumbo-frames with my e1000e network interface.

 $ sudo ip link set eth1 mtu 9000
 RTNETLINK answers: Invalid argument
 
Card-info (from kernel-log)

 e1000e 0000:05:00.1: eth1: (PCI Express:2.5GT/s:Width x4) 00:1b:78:59:84:25
 e1000e 0000:05:00.1: eth1: Intel(R) PRO/1000 Network Connection
 e1000e 0000:05:00.1: eth1: MAC: 0, PHY: 4, PBA No: D51930-003

I have bisected and found:

 70495a500d787c0c90a136acf454cb7d0eecd82e is the first bad commit

Comment 1 Christer Ekholm 2012-05-22 18:45:00 UTC

Solved.

As the commitmessage actually says, and also kernel-message:

e1000e 0000:05:00.1: eth1: Jumbo frames cannot be enabled when both receive checksum offload and receive hashing are enabled.  Disable one of the receive offload features before enabling jumbos.

Setting rxhash to off works.

$ sudo ethtool -K eth1 rxhash off

$ sudo ip link set eth1 mtu 9000


-- 
 Christer