Is enabling jumbo frames on RTL8111C possible?

[Krzysztof Dajka]

Hi,

I'm trying to enable jumbo frames on my re0 NIC. I tried:
# ifconfig re0 mtu 1600
ifconfig: ioctl (set mtu): Invalid argument

I have found in /usr/src/sys/dev/re/if_re.c
 /*
* These controllers support jumbo frame but it seems
* that enabling it requires touching additional magic
* registers. Depending on MAC revisions some
* controllers need to disable checksum offload. So
* disable jumbo frame until I have better idea what
* it really requires to make it support.
* RTL8168C/CP : supports up to 6KB jumbo frame.
* RTL8111C/CP : supports up to 9KB jumbo frame.
*/

pciconf -lv shows:
re0 at pci0:2:0:0: class=0x020000 card=0xe0001458 chip=0x816810ec rev=0x02
hdr=0x00
vendor = 'Realtek Semiconductor'
device = 'Gigabit Ethernet NIC(NDIS 6.0) (RTL8168/8111/8111c)'
class = network
subclass = ethernet

Do I need to set some quirks in boot process to enable jumbo frames, or it
cannot be done because it's not implemented in the driver.
I tried setting larger mtu than 1500 on Debian Squeeze and it worked well,
so definitely my chip supports jumbo frames