John Ogness <john.ogness@xxxxxxxxxxxxx> writes: > On 2024-04-02, Esben Haabendal <esben@xxxxxxxxxx> wrote: >>> printk() tries to print directly from the calling context. Are you >>> experiencing problems where you do not see the restarting message? >> >> Yes, that is exactly what we are seing. >> >> It is an i.MX8MP system, and console is attached to ttymxc1 >> (drivers/tty/serial/imx.c). >> >> Booting up, and simply executing "reboot" command. Without these two >> patches, the "reboot: Restarting system" message is not written to >> ttymxc1 console. With the patches, it is. > > This console driver is using the legacy console interface. For > PREEMPT_RT, legacy consoles run exclusively as a thread and thus may not > have a chance to flush messages before a shutdown/reboot. The correct > solution is to port the driver to the new nbcon console interface. I see. The `if (IS_ENABLED(CONFIG_PREEMPT_RT))` in console_unlock() is preventing the console_lock/console_unlock dance to do what I need. Are there any other examples other than 8250 for how to port a driver to nbcon? What is the plans for porting all of this to mainline? Should all drivers be ported first, or will a solution to prevent this type of regression be implemented at some later time? /Esben
