[U-Boot] [PATCH 29/32] nitrogen6x: config: configure usb_ether

[Stefano Babic]

Hi Eric,

On 06/10/2014 18:41, Eric Nelson wrote:

>> I understand the use case, but it does not always work (I mean, in all
>> network configurations) and we regret generally having IP addresses hard
>> coded in the default configuration.
>>
> 
> Can you clarify which parts (mac/IP address/both) are a problem?
> 
> The 'usb_ether' is kind of an odd beast, in that it's a link-local
> protocol, which is why the the IP addresses aren't read from or written
> to a persistent environment.

This is not completely true. I mean, I understand that you want to have
such as situation, with addresses valid only in the link host / target.

However, if a customer / user has a PC belonging to the  10.0.0.0/24
network, there is a conflict. And this is not a rare case, because as I
have seen in companies 10.0.0.0/8 are used more often as 192.168.0.0/16.

You can have two interface (ethernet and USB) acting on the same address
range and packets originally sent to network are readdressed to the
target, letting the customer without network.

I understand that you want to provide is a special case - but as you can
see, you cannot cover all cases by setting a hard coded address.

> 
> Our goal was to only require configuration of one side of the link
> (the USB Host). It seems that without implementing a DHCP **server**,
> this is the most convenient.

If you really want, why don't you use a script as a 6x_ ? usbrecover can
load initially a script setting the network addresses, without
hardcoding to the u-boot image.

> 
> The mac addresses above are ours, and we can confirm that they are
> not in use on any other hardware,

I know that and it is exactly the same we had in the past with other
boards. Customers can buy more as one instance of the boards, having
then multiple boards with the same MAC address - and very bad case.


> so they're guaranteed to be unique
> unless you happen to hook up multiple of our boards to a Host at the
> same time.

Yes, exactly. Why do you want to restrict your sales chances ? :-D

Seriously, hard coding mac and network addresses was strictly rejected -
even if after your patch I have found a couple of boards doing that
(maybe it was not seen during review, see for example  v38b.h).

> 
> Since the configuration of network adapters on most hosts is based
> on mac addresses, hard-coding these prevents the need to re-configure
> each time a new board is connected to a host.

I understand that hard coding makes life easier, but I am not convinced
it is the correct way to do, specially with IP addresses.

Best regards,
Stefano Babic


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