Gathering Information from a Running System, Using only NMI (x86)
In order to force a crash dump form a system that seems hung or frozen e.g. no longer has has interactive capabilities if your system supports NMI (hardware button, service processor command) it it might be a good practice to permanently configure the following:
- Adding the line (as user root) "set pcplusmp:apic_panic_on_nmi = 1" to your /etc/system file allows a crash dump to be generated on the receipt by your system of an NMI (non-maskable interrupt). Once this line is added you will have to do a reconfiguration reboot.
- Note, If you also have the line"set pcplusmp:apic_kmdb_on_nmi=1" in your /etc/system file you will not generate a crash dump, but rather go into the kernel debugger as this later directive takes priority over the pcplusmp:apic_panic_on_nmi setting.
The above might be a a very good practice as it simplifies forcing a "crash dump" (avoids the x86 requirement of keyboard input e.g. press 'Shift-Pause'; or 'Esc-B'; or 'F1', then 'A'.). However this simplification will a) not work on all platforms and b) might even cause issues on a few system types and c) works if your system loads/uses the pcplusmp module (not the apix module). Because of these requirements despite the fact that many admins use this as a default setting it is not the default configuration for fresh installs of the OS.