[U-Boot] [PATCH 0/3] Net Boot Controller

[Stefano Babic <sbabic@denx.de>]

On 11/17/2010 02:17 PM, tristan wrote:
>     Is NBC a standard ? Could you provide a link describing this protocol ?
> 
> 
> NBC is not a standard, this is just a simple protocol I designed for
> this purpose

IMHO we should not add such as protocol to u-boot, considering that
u-boot already implements standard ways (DHCP, BOOTP) to achieve what
you want.
Your solution works only locally and you have to synchronize yourself to
send the broadcast message when you reset the board. DHCP works in anyway.

Michael sent an example how to switch the console to NetConsole. Is it
not suitable for you ? You could add the dhcp command to the preboot
variable if you need to obtain an IP address after a reset.

> I did think about using DHCP for this, but finally decided to use a new
> packet format since the use is very specific and using DHCP 

Not really, Your protocol is a way to set the IP address, after that you
switch the console. Providing network addresses is exactly the DHCP's job.

> All the packets are sent to the broadcast adress, so if two boards are
> waiting at the same time there will be a conflict. 

This is not good...

> The way to use it in my mind is to start broadcasting with sendnbc, and
> then start the board.
> As the sendnbc tool will stop broadcasting right after one target
> answered to the packet by sending back the u-booy prompt, the only case
> that can lead to this problem is if both targets are started exactly at
> the same time.

It not so uncommon to have a lot of boards connected to the same
network. If all of them support your protocol, we get in big trouble.

Best regards,
Stefano Babic

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