Think i just experienced the wierdest ever bug at work.
Were running a Yocto yada yada what ever platform, and we recently upgrade the kernel.
This absolutely devastated any software i’ve added to the platform.
turns out that during boot, roughly around the time init.d does it’s stuff it allows for init.d to launch scripts while the kernel itself is in a sort of panic state, but recovers from this state, but anything executed here, is just Fked it starts, but ‘ps ax | grep “what ever”’ shows the program running, but appearently in some “i am trying to start up state” but still active as a application.
It didnt dawn on me until i put a ‘sleep X && run some application’ into the init.d script and PS ax showed the init.d command e.g. ‘Sxysomescript start’, and just hung in that script, what was going on.
how do you debug a kernel which allows software to start with no errors, but just hangs them during boot.
The linux kernel changed a bunch of hang ons to warn-ons for fundamental state stuff a while back, and the answer is that you can’t really.