Diagnosing dhcpcd crashes [was Re: Looking to address two networking issues with NetBSD 10]

[Taylor R Campbell <campbell+netbsd-tech-net%mumble.net@localhost>]

> Date: Fri, 18 Oct 2024 21:51:53 +0000 (UTC)
> From: John Klos <john%klos.com@localhost>
> 
> We still have two large issues with networking with NetBSD 10. One is that 
> dhcpcd exits and needs to be restarted manually or programmatically when 
> it does. This issue was discussed here:
> 
> https://mail-index.netbsd.org/tech-net/2024/03/18/msg008729.html
> 
> It seems dhcpcd exiting corresponds to getting a new lease / IP (it 
> doesn't exit on networks where the address never (or rarely) changes).

There is an open PR tracking the difficulty of diagnosing when dhcpcd
spontaneously exits:

PR kern/57952: dhcpcd(8) inexplicably terminated in the night
https://gnats.NetBSD.org/57952

Somewhere in there is a recipe for convincing dhcpcd to dump core when
it crashes, rather than silently exit or unceremoniously leave an
opaque log message.  That would be a good first step, unless roy@ has
other suggestions for making the logging about exit reasons more
obvious.