On Sat, Nov 16, 2019 at 9:31 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > On 11/15/19 7:03 PM, Muni Sekhar wrote: > [ ... ] > >> > >> Another possibility, of course, might be to enable a hardware watchdog > >> in your system (assuming it supports one). I personally would not trust > >> the NMI watchdog because to detect a system hang, after all, there are > >> situations where even NMIs no longer work. > > > >>From dmesg , Is it possible to know whether my system supports > > hardware watchdog or not? > > I assume that my system supports the hardware watchdog , then how to > > enable the hardware watchdog to debug the system freeze issues? > > > > Hardware watchdog support really depends on the board type. Most PC > mainboards support a watchdog in the Super-IO chip, but on some it is > not wired correctly. On embedded boards it is often built into the SoC. > The easiest way to see if you have a watchdog would be to check for the > existence of /dev/watchdog. However, on a PC that would most likely > not be there because the necessary module is not auto-loaded. > If you tell us your board type, or better the Super-IO chip on the board, > we might be able to help. I’m having two same configuration systems, in one system I installed the Vanilla kernel and I see the /dev/watchdog and /dev/watchdog0 nodes. In other system I’m running with ubuntu distribution kernel, but I don’t see any watchdog device node. So it looks like I need to manually load the kernel module in distro kernel. Is there a way to know what is the corresponding kernel module for /dev/watchdog node? # ls -l /dev/watchdog* crw------- 1 root root 10, 130 Nov 15 17:15 /dev/watchdog crw------- 1 root root 248, 0 Nov 15 17:15 /dev/watchdog0 # ps -ax | grep watchdog 678 ? S 0:00 [watchdogd] Regarding Super-IO chip, how to find out the Super-IO chip model? > > Note though that this won't help to debug the problem. A hardware > watchdog resets the system. It helps to recover, but it is not intended > to help with debugging. How do I use the hardware watchdog to reset my system when system is frozen? It helps me to collect the crashdump and finally helps me to find the root cause for the system frozen issue. > > Guenter -- Thanks, Sekhar
