[SLOF] [PATCH 0/6] net-snk: More IPv6 fixes and improvements

[Thomas Huth]

On 14.01.2016 09:18, Alexey Kardashevskiy wrote:
[...]
> For my tests I have a virtual bridge which is not connected anywhere,
> and 3 guests:
> 
> 1. "dhcpv6" guest, fc23, one interface, attached to bridge#1, static IP
> (fd00:4149:4b00::1), running dmasq with DHCP on and TFTP off, with RA
> and everything.
> 
> 2. "tftp" guest, fc23, two interfaces - one is attached to bridge#1 and
> received IPv6 via DHCP (fd00:4149:4b00::bc), another interface is not
> attached anywhere and has a static IP (d00:4149:4b01::1); this guest is
> also running dnsmasq but DHCP is off there and TFTP is on.
> 
> 3. test guest to boot via IPv6 (so - only SLOF, no disk image or
> initramdisk), one interface, attached to the same bridge, it gets IP
> over DHCP (fd00:4149:4b00:0:c041:49ff:fe4b:5 - which is quite weird but
> ok) and it receives TFTP image name via dhcp6 and tries downloading it
> but fails.
> dnsmasq.conf:
> dhcp-option=option6:59,tftp://[fd00:4149:4b01::1]/image.aiktest0
> 
> 
> If I move TFTP from 2 to 1 (i.e. from fd00:4149:4b01::1 to
> fd00:4149:4b00::1), then SLOF can download the image and boot.
> 
> I tried pinging fd00:4149:4b01::1 from guest#3 (booted it from a disk
> image, received fd00:4149:4b00::bd from dhcp), it worked so routing
> works fine (I added a route and enabled forwarding on guest#1).

Sounds like all guests are connected to the same network (bridge 1)? So
I think no routing is involved here at all, just the TFTP server is
different from the DHCPv6 server? Something like this:

+------+                              +--------+
|      |         +---------+          |        |
| SLOF +---------+ bridge1 +----------+ DHCPv6 |
|      |         +----+----+          | &radvd |
+------+              |               +--------+
                      |
               +------+----+
               |           |
               |   TFTP    |
               |           |
               +-----------+

For testing routing, I think you'd rather need to set up routing on the
radvd server for example:

+------+                              +--------+
|      |         +---------+          |        |
| SLOF +---------+ bridge1 +----------+ DHCPv6 |
|      |         +----+----+          |        |
+------+              |               +--------+
                      |
               +------+-----+    +-------+
               |            |    |       |
               |   radvd    +----+ TFTP  |
               |            |    |       |
               +------------+    +-------+


Anyway, can you download a file via TFTP from 2 when 3 is booted into
Linux (using a normal TFTP client program)? ... just to make sure that
TFTP really works from 2 and is not blocked by a firewall on 2 or
something similar.

> It seems that SLOF just fails to use the default route. The code is
> there, just needs some debugging...

Could you either use wireshark on 1 and 2 to log the network traffic, or
try the new filter-dump [1] on 3 to get a dump with the packets from
SLOF? ... then we could see whether SLOF gets the destination MAC
addresses right when sending packets to the TFTP server.

 Thomas

[1] See http://comments.gmane.org/gmane.comp.emulators.qemu/368614 for
an example how to use it.