e1000g jumbo frames don't work with 82579LM
It appears the e1000g driver does not work with jumbo frames with the Intel 82579LM chipset.
I discovered this issue today with a SuperMicro X9SCM-F motherboard which has an Intel 82579LM and an Intel 82574L. My /kernel/drv/e1000g.conf has the correct MaxFrameSize=3,3,0... but I was experience odd network connectivity issues with only one of the NICs (e1000g1 in this case). I reverted back to the default MTU in sheer desperation and everything started working.
mgbowman@oi_151a4:~$ dladm show-linkprop -p mtu LINK PROPERTY PERM VALUE DEFAULT POSSIBLE e1000g0 mtu rw 9000 1500 1500-9216 e1000g1 mtu rw 1500 1500 1500-9216
I tried various MTUs on the e1000g1 interface and nothing but the 1500 works. Intel says both NICs have Jumbo Frame support so this make me suspect it's a driver issue.
Updated by Enrico Papi almost 9 years ago
on oi-151a4, after setting MaxFrameSize=0 and rebooting in noticed the system has already set MTU to:
dladm show-linkprop -p mtu
LINK PROPERTY PERM VALUE DEFAULT POSSIBLE
e1000g0 mtu rw 9216 1500 1500-9216
(don't know if this should happen)
my 82579LM NIC looks OK according dladm/ipadm status, but the system does not receive/send packets.
setting back MaxFrameSize=0, and rebooting, fixes the problem,
sorry but i can not test further here in this system, for example unplumbing the NIC, or removing active interfaces/links on it and setting a different MTU manually.....
Updated by Matthew Bowman almost 9 years ago
Did you mean after setting MaxFrameSize = 3 and rebooting you noticed the system had already set the MTU? This happened for me as well but I chalked it up to auto negotiated between my JF enabled switch and the NIC.
Just wanted to add that if you have MaxFrameSize=3 and manually set the MTU to 1500 (my current setup), everything works as expected.