linux-2.6.10, ppc8280, odd ARP request

linux-2.6.10, ppc8280, odd ARP request

[Richard Danter]

Hi All,

I am seeing an odd ARP request from an 8280 when using any of the FCC's 
as eth0. Using SCC1 as eth0 seems fine.

My board boots using U-Boot. It tftp loads the kernel image via FCC2, so 
I know the FCC's are working (I have tested the others too). This part 
is fine, but once the kernel has loaded it tries to NFS mount the root 
filesystem. When it gets to the point of looking up the RPC port it 
first sends an ARP request for the server. When eth0 is any of the FCC's 
I see a 59 byte packet on the wire (using ethereal). The server either 
does not see the packet or just ignores it so there is no reply to the 
board.

When I boot using SCC1 as eth0 the ARP request sent is 60 bytes long. It 
is replied to and the NFS mount works.

I noticed that U-Boot also sends an ARP request before the tftp download 
starts and it is 60 bytes long using both SCC and FCC ports. But as far 
as I know, ARP requests can be varying length (the last few bytes seem 
to be just padding).

Has anyone else seen anything like this? Any pointers where I should look?

Many thanks,
Rich

Re: linux-2.6.10, ppc8280, odd ARP request - solved

[Richard Danter]

Richard Danter wrote:
> 
> My board boots using U-Boot. It tftp loads the kernel image via FCC2, so 
> I know the FCC's are working (I have tested the others too). This part 
> is fine, but once the kernel has loaded it tries to NFS mount the root 
> filesystem. When it gets to the point of looking up the RPC port it 
> first sends an ARP request for the server. When eth0 is any of the FCC's 
> I see a 59 byte packet on the wire (using ethereal). The server either 
> does not see the packet or just ignores it so there is no reply to the 
> board.
> 
> When I boot using SCC1 as eth0 the ARP request sent is 60 bytes long. It 
> is replied to and the NFS mount works.
> 
> I noticed that U-Boot also sends an ARP request before the tftp download 
> starts and it is 60 bytes long using both SCC and FCC ports. But as far 
> as I know, ARP requests can be varying length (the last few bytes seem 
> to be just padding).

Looks like the problem may be with the setup of the FCC, particularly 
with working out what speed to run at. I connected my board to a 
100BaseT hub and it worked perfectly. It was failing when I was using an 
older 10BaseT hub. In both cases the hub is a Netgear and I have never 
had a problem with any other board or PC.

Odd how it effects Linux but not U-Boot. Seems to indicate a driver 
issue anyway.

Rich