Fiber port with a strange problem in Linux 2.4.18

My firewall is based linux and with kernel of 2.4.18,
and when I connected Fiber port on the firewall with Switch I found a strange 
problem;

as you know fiber port will automatically setting
the speed with 1000M,and duplex with full,if connetcted,

But I am confused with the function of autoneg,
By default the autoneg for this fiber port is settled with Off,
But after I turned autoneg  on with the ethtool
I found I can not turn this back to OFF,
Only after reboot the system autoneg will turn to off.

shown as below:

 / >ethtool eth1  (this is fiber 1000sx port)
Settings for eth1:
        Supported ports: [ FIBRE ]
        Supported link modes:   1000baseT/Full 
        Supports auto-negotiation: Yes
        Advertised link modes:  1000baseT/Full 
        Advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: FIBRE
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: off
        Supports Wake-on: umbg
        Wake-on: d
        Link detected: yes

But after I tunrned the autoneg to ON:

ethtool -s eth1 autoneg on

I can not make the autoneg for this port turn back to OFF;
even I input the command;

ethtool -s eth1 aotuneg off

It wil do nothing;

Only after reboot the system,It will be back to Off.

Is this a bug for this kernel?or for ethtool ?

Thanks for your help.



from kent