Re: Making dhcpcd work on diskless clients

[Roy Marples <roy%marples.name@localhost>]

On 10/02/2015 04:25, Alan Barrett wrote:
> On Sun, 08 Feb 2015, Roy Marples wrote:
>>> since this problem goes away if we make all of dhcpcd in-memory first,
>>> possibly what happens here is that with i386 or amd64, the layout is
>>> such that we don't ever try to fault in code during the small period
>>> of time that the route is missing.
>>
>> I don't fully understand what you are saying.
> 
> Some part of the code that you are trying to run may not be in memory,
> so you may encounter a page fault when you try to run it.  Responding to
> the page fault involves reading information from the the file system. 
> On a diskless client, reading from the file system actually involves
> transferring data over the network from the remote file server.  If you
> try to read from the file server at a time when the routing table does
> not contain a usable route to the file server, then you lose.
> 
>> But do you have an idea of how this can be fixed then without dhcpcd
>> having to learn the routing table at load time?
> 
> Do you currently use RTM_DELETE and RTM_ADD?  Can you use RTM_CHANGE
> instead?

The last time I tried using RTM_CHANGE, it did not clear the learned
cloned routes which RTM_DELETE handily does for me. This is important if
we need to move a subnet route from one interface to another.

Roy