Andrew Lunn wrote:
> On Wed, Jan 23, 2008 at 04:11:11PM +0000, Dave Lawrence wrote:
>> I can't seem to get DHCP work over multiple interfaces.
> 
> The eCos DHCP client used to work with multiple interfaces. This is
> why there is the half up states, so that it can force the packet out
> the correct interface and the clearing of routes when performing DHCP
> transactions.
> 
> If it does not work, i suggest you work your way back and see which
> patch broke it.
> 
>       Andrew
> 

I had a look on an older platform that uses an older ecos tree.  It does 
work but there were some problems:
  * Packets could come out on the wrong interface if two threads were 
simultaneously calling do_dhcp (on different interfaces)
  * Our application was also interfering with the routing tables in 
response to detecting devices going up / down

So I don't have any opinion about whether my fixes are of use to the 
wider ecos world but I've attached a patch in case.  It does the following:

* Provide dhcp_get_lock and dhcp_release_lock as global functions which 
the application can use to ensure interference is avoided
* Use these functions at the entry and exit points of do_dhcp to prevent 
it functioning reetrantly (is that a word?)

Unfortunately I'm no closer to fixing the original problem - on my new 
platform packets for 255.255.255.255 *always* come out on eth1.

Was I correct to continue with this thread or should I have switched to 
the patches list?