Hi Tom, On Thu, Mar 7, 2019 at 10:38 PM Tom Li <tomli@xxxxxxxx> wrote: > On Thu, Mar 07, 2019 at 10:39:23AM +0100, Geert Uytterhoeven wrote: > > On Thu, Mar 7, 2019 at 10:00 AM Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote: > > > It's possible to do this using a reboot notifier. I am not sure if there > > > are better ways to achieve the same, but there's at least one example of > > > using reboot notifiers to achieve the exact same goal. > > > > > > See drivers/video/fbdev/aty/atyfb_base.c, look for > > > register_reboot_notifier(). > > > > Or a shutdown handler, which is more device-centric? > > (cfr. "[3/4] fbdev: atafb: Fix broken frame buffer after kexec", > > https://patchwork.kernel.org/patch/10814381/). > > > > Gr{oetje,eeting}s, > > Thanks, I knew reboot_notifier but I thought it feels "hacky" to use it in a > device driver, shutdown() handler looks better. > > Nevertheless, does it mean there's no way to prevent it from happening if the > user issues a emergency reboot? Like an automatic reboot after a kernel panic, > or a SysRq-B reboot. If Linux performs a reboot, it calls the shutdown handlers. I think that includes reboot on panic, or SysRq-B, but I'd have to check to be 100% sure. If the kernel just crashes, of course all of that doesn't happen. Is your graphics card reset when the reset button is pressed, or only on cold power on? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
