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

[tristan]

Hi Stefano,

2010/11/17 Stefano Babic <sbabic at denx.de>

> On 11/16/2010 07:04 PM, tristan.lelong at blunderer.org wrote:
> > From: Tristan Lelong <tristan.lelong at blunderer.org>
> >
> > This patch allow to interrupt u-boot autoboot from remote PC and
> auto-reconfigure a netconsole redirected to this remote PC
> >
> > Tristan Lelong (3):
> >   Add support for Net Boot Controller (NBC) packet
> >   Add sendnbc tool to broadcast NBC magic packet
> >   Add the NBC + netconsole corresponding documentation
> >
>
> Hi Tristan,
>
> >  common/main.c         |    5 +
> >  doc/README.netconsole |   66 +++++++++++++++
> >  include/net.h         |    6 +-
> >  net/Makefile          |    2 +
> >  net/nbc.c             |  143 ++++++++++++++++++++++++++++++++
> >  net/nbc.h             |   39 +++++++++
> >  net/net.c             |   17 ++++
> >  tools/Makefile        |    6 ++
> >  tools/sendnbc.c       |  219
> +++++++++++++++++++++++++++++++++++++++++++++++++
> >  9 files changed, 502 insertions(+), 1 deletions(-)
> >  create mode 100644 doc/README.netconsole
> >  create mode 100644 net/nbc.c
> >  create mode 100644 net/nbc.h
> >  create mode 100644 tools/sendnbc.c
>
> 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


>
> I am quite confuse, this seems a way to replace DHCP in a simplest form
> to set up the ip address using some sort of knocking-port. As additional
> feature, the


> Why cannot we reach the same result using the "Vendor Specific
> Information" (or another option field) of DHCP answer ? You can set
> there some infos that the target could understand.
>

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


>
> It seems to me that the first packet is always sent to the broadcast
> address. What happens if we have two boards on the network, both waiting
> in autoboot ? Do they obtain the same ip address ?
>

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

Indeed there could be some potential improvement on this conflicted
situation.

Regards


>
> Best regards,
> Stefano Babic
>
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