Package: kdump-tools Version: 1:1.5.3-2 Dear Maintainer,
The documentation provided in kdump-tools package states nmi_watchdog should be set to 1 in kernel command line on x86 and x86_64 architectures. http://sources.debian.net/src/makedumpfile/1:1.5.9-5/debian/kdump-tools.README.Debian/#L58 Correct me if I'm wrong, but the goal is to call kernel panic when the watchdog detects the system is stalled, right? As far as I can understand kernel source code, nmi_watchdog=1 is actually the default in Debian kernels. - On jessie (3.16.7-ckt25-2): http://sources.debian.net/src/linux/3.16.7-ckt25-2/kernel/watchdog.c/#L32 The nmi_watchdog parameter logic is in hardlockup_panic_setup() which does basically nothing for nmi_watchdog=1. - On stretch (4.5.3-2): http://sources.debian.net/src/linux/4.5.3-2/kernel/watchdog.c/#L50 The NMI watchdog is enabled as long as CONFIG_HARDLOCKUP_DETECTOR is set, and it is set on x86 and x86_64. The nmi_watchdog=1 seems to be useless for all kernels on this architecture. For the panic call on NMI watchdog thing, the default value is controlled by CONFIG_BOOTPARAM_HARDLOCKUP_PANIC. It is not set in debian kernels: http://sources.debian.net/src/linux/4.5.3-2/debian/config/config/#L5741 Then, the NMI watchdog won't call panic by default. However, the logic in hardlockup_panic_setup() tells it can be enabled with nmi_watchdog=panic in kernel command line tough. If I'm hopefully right in all my guesses, my conclusion is that kdump-tools documentation should recommend setting nmi_watchdog=panic in kernel command line on x86 and x86_64. I'm looking forward to reading from you soon! Best, Rémi
