Re: mtu issue with tg3 in anaconda-11.1.2.87 for centos 5

[Jeroen van Meeuwen <kanarip kanarip com>]

Paul Armor wrote:
> Hi,
> we're trying to kickstart centos 5 on machines with broadcom 5704's, 
> using jumbo mtu's (mtu=4500).
>
> We're setting the option mtu=4500 which is being passed to the kernel by 
> pxelinux, and then we also set mtu=4500 in the ks.cfg.
>
> Perhaps I'm looking in the wrong place, but from looking at 
> loader2/loader.c, I think we're doing things properly (this worked with 
> FC4's anaconda, but is failing in Cent5).
>
>
> If I set it to dhcp in the pxelinux config file AND set the mtu=4500, it 
> dhcp's, but forgets the mtu.  If I set a static IP/netmask/mtu in the 
> pxelinux config file, it works as expected.
>
> Is this to be expected?  Is this a bug?

MTU is actually a valid setting a DHCP server can pass onto it's 
clients, so I suspect this is expected behavior:

From http://linux.die.net/man/5/dhcp-options:

option interface-mtu uint16;

    This option specifies the MTU to use on this interface. The minimum 
legal value for the MTU is 68.

Kind regards,

Jeroen van Meeuwen
-kanarip