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How robust is either the proposed: `panic=60` or the Linux API described in sibling comments? I run into kernel panics a lot and usually power cycle the machin

How robust is either the proposed: `panic=60` or the Linux API described in sibling comments? I run into kernel panics a lot and usually power cycle the machine. In particular for this to reboot after the kernel dies it seems to need real hardware support. Ping this register every N seconds or I reboot style. Is that what we're working with here, vs some other part of the kernel which might survive part of it dying? > docs here suggest the system can get in a state which ignores the watchdog, https://mjmwired.net/kernel/Documentation/nmi_watchdog.txt https://mjmwired.net/kernel/Documentation/nmi_watchdog.txt > thread here suggests a bug in the bios can stop a watchdog working https://community.intel.com/t5/Intel-NUCs/Issue-with-Linux-watchdog-timer-where-system-did-not-restart/td-p/1243160 https://community.intel.com/t5/Intel-NUCs/Issue-with-Linux-w...

ilyt 4y ago
> I run into kernel panics a lot Where ? The most I saw was when trying to boot something untypical. > Is that what we're working with here, vs some other part of the kernel which might survive part of it dying? I'd imagine it's same path for panic. There is probably still ways to crash (especially with hardware faults) to get around it so it isn't replacement for watchdog but it looks like an improvement > docs here suggest the system can get in a state which ignores the watchdog, https://mjmwired.net/kernel/Documentation/nmi_watchdog.txt https://mjmwired.net/kernel/Documentation/nmi_watchdog.txt I'd like to say you need "proper" external watchdog like IPMI based one on server but * They still need to get thru the boot for kernel to activate them in the first place. I think I saw some servers that had some extra protection to crash on boot but definitely not anything common * I've seen weird bugs around those too. Like older IBM servers could trigger watchdog when you synchronized IPMI time You really kinda need 2 watchdog loops, long one (say 5-10 minutes) that runs from start catering to "something crashed during boot", and short one (few seconds to maybe a minute) that gets activated once kernel and OS is up and running

ilyt 4y ago

> I run into kernel panics a lot Where ? The most I saw was when trying to boot something untypical. > Is that what we're working with here, vs some other part of the kernel which might survive part of it dying? I'd imagine it's same path for panic. There is probably still ways to crash (especially with hardware faults) to get around it so it isn't replacement for watchdog but it looks like an improvement > docs here suggest the system can get in a state which ignores the watchdog, https://mjmwired.net/kernel/Documentation/nmi_watchdog.txt https://mjmwired.net/kernel/Documentation/nmi_watchdog.txt I'd like to say you need "proper" external watchdog like IPMI based one on server but * They still need to get thru the boot for kernel to activate them in the first place. I think I saw some servers that had some extra protection to crash on boot but definitely not anything common * I've seen weird bugs around those too. Like older IBM servers could trigger watchdog when you synchronized IPMI time You really kinda need 2 watchdog loops, long one (say 5-10 minutes) that runs from start catering to "something crashed during boot", and short one (few seconds to maybe a minute) that gets activated once kernel and OS is up and running