On 18/05/2022 04:33, Petr Mladek wrote: > [...] > Anyway, I would distinguish it the following way. > > + If the notifier is preserving kernel log then it should be ideally > treated as kmsg_dump(). > > + It the notifier is saving another debugging data then it better > fits into the "hypervisor" notifier list. > > Definitely, I agree - it's logical, since we want more info in the logs, and happens some notifiers running in the informational list do that, like ftrace_on_oops for example. > Regarding the reliability. From my POV, any panic notifier enabled > in a generic kernel should be reliable with more than 99,9%. > Otherwise, they should not be in the notifier list at all. > > An exception would be a platform-specific notifier that is > called only on some specific platform and developers maintaining > this platform agree on this. > > The value "99,9%" is arbitrary. I am not sure if it is realistic > even in the other code, for example, console_flush_on_panic() > or emergency_restart(). I just want to point out that the border > should be rather high. Otherwise we would back in the situation > where people would want to disable particular notifiers. > Totally agree, these percentages are just an example, 50% is ridiculous low reliability in my example heheh But some notifiers deep dive in abstraction layers (like regmap or GPIO stuff) and it's hard to determine the probability of a lock issue (take a spinlock already taken inside regmap code and live-lock forever, for example). These are better to run, if possible, later than kdump or even info list. Thanks again for the good analysis Petr! Cheers, Guilherme
