On 2021-11-10, Daniel Vetter <daniel@xxxxxxxx> wrote: > I'm a bit out of the loop but from lwn articles my understanding is > that part of upstreaming from -rt we no longer have the explicit "I'm > a safe console for direct printing" opt-in. Which I get from a > backwards compat pov, but I still think for at least fbcon we really > should never attempt a direct printk con->write, it's just all around > terrible. Right now we don't have an explicit "I'm a safe console for direct printing" option. Right now all printing is direct. But it sounds to me that we should add this console flag when we introduce kthread printers. > So yeah for fbcon at least I think we really should throw out direct > con->write from printk completely. Even after we introduce kthread printers, there will still be situations where direct printing is used: booting (before kthreads exist) and shutdown/suspend/crash situations, when the kthreads may not be active. I will introduce a console flag so that consoles can opt-out for direct printing. (opt-out rather than opt-in is probably easier, since there are only a few that would need to opt-out). Since kthread printers do not yet exist (hoping to get them in for 5.17), I am not sure how we should address the reported bug for existing kernels. John Ogness
