making SCTP loadable and removing it from GENERIC

[Doug Hardie]

> On 9 July 2020, at 14:45, Michael Tuexen <tuexen at freebsd.org> wrote:
> 
>> On 9. Jul 2020, at 23:15, Doug Hardie <bc979 at lafn.org> wrote:
>> 
>> Actually, the users of these systems would have no clue about that message.  All they would figure out is that the system is down and they can't do their job and bitch to the CEO.  I am going to assume that that error will be produced by the socket call and I have added code to check for it and email me if it occurs.  I believe that the only viable approach for us is the rc.conf solution as some of these systems are rhapsberry pi 3s which I understand don't use the loader.conf file.
> OK. Do you control the kernel which is running on the machines? If that is the case,
> you could add a line to the kernel config, rebuild the kernel and use that custom
> kernel with compiled-in SCTP support. That is still possible.

As best as I can tell, compiling a non-generic kernel may not be easily done.  The Pi's are not located anywhere near me and it would be extremely difficult to deal with any kernel issues.  I prefer to live with generic kernels.  Life has been much easer since I switched to them.

>> 
>> One of the configurations we are considering is for each user to have their own Rhapsberry Pi and eliminate the central server.  All data is replicated between all the machines so there is no need for a central server anymore.  If I can make that work, it would be a large cost savings for my client.
> If that gets rid of the need to use SCTP, that would also work.

SCTP is the heart of the replication system.  I had numerous problems trying to get UDP to work.  The record sizes can be up to 28 Mb.  I think it is theoretically possible to be even larger, but I have never seen any over 28 Mb.  SCTP handles that just fine.  It also handles multi-homing which we also use.

-- Doug