[dm-devel] Serial console is causing system lock-up

[John Ogness]

On 2019-03-12, Petr Mladek <pmladek at suse.com> wrote:
> On Tue 2019-03-12 09:17:49, John Ogness wrote:
>> The current printk implementation is handling all console printing as
>> best effort. Trying hard enough to dramatically affect the system,
>> but not trying hard enough to guarantee success.
>
> I agree that direct output is more reliable. It might be very useful
> for debugging some types of problems. The question is if it is worth
> the cost (code complexity, serializing CPUs == slowing down the
> entire system).
>
> But it is is possible that a reasonable offloading (in the direction
> of last Sergey's approach) might be a better deal.
>
>
> I suggest the following way forward (separate patchsets):
>
>     1. Replace log buffer (least controversial thing)
>     2. Reliable offload to kthread (would be useful anyway)
>     3. Atomic consoles (a lot of tricky code, might not be
> 		worth the effort)
>
> Could we agree on this?

Since this is about the new RFC printk design, I've responded in that
thread [0].

John Ogness

[0] https://lkml.kernel.org/r/874l8815uc.fsf@linutronix.de