On 24/09/2019 03.37, James Knott wrote:
On 2019-09-23 09:26 PM, Carlos E. R. wrote:
preferably with REISUB
What is "REISUB"?
<https://en.wikipedia.org/wiki/Magic_SysRq_key#Uses> About enabling: <https://www.suse.com/documentation/opensuse121/book_security/data/sec_security_yast_security_misc.html> +++.............. Enable Magic SysRq Keys The magic SysRq key is a keycombo that enables you to have some control over the system even when it has crashed. The complete documentation can be found at /usr/src/linux/Documentation/sysrq.txt (requires installation of the kernel-source package). ..............++- <http://opensuse.14.x6.nabble.com/Magic-Sysrequest-gone-td5081027.html> +++.............. Hints from here (Disabled by Default): https://forums.opensuse.org/showthread.php/510867-Is-Alt-SysRq-REISUB-disabl... It's stored in sysctl, as kernel.sysrq, check via "/usr/sbin/sysctl -a --pattern kernel.sysrq" (works as normal user) a value of "0" (zero) means disabled, a value of "1" (one) means enabled. ..............++- Or here: <https://linuxconfig.org/how-to-enable-all-sysrq-functions-on-linux> Check: Telcontar:~ # /usr/sbin/sysctl -a --pattern kernel.sysrq kernel.sysrq = 1 Telcontar:~ # or cat /proc/sys/kernel/sysrq Enable, in short: echo 1 > /proc/sys/kernel/sysrq For the current session. Permanent: Telcontar:~ # l /etc/sysctl.d/99-sysctl.conf lrwxrwxrwx 1 root root 16 Feb 25 2014 /etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf Telcontar:~ # Telcontar:~ # cat /etc/sysctl.d/99-sysctl.conf | grep sysrq kernel.sysrq = 1 Telcontar:~ # kernel verification: Telcontar:~ # grep -i CONFIG_MAGIC_SYSRQ /boot/config-4.12.14-lp151.28.13-default CONFIG_MAGIC_SYSRQ=y CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE=0x1 CONFIG_MAGIC_SYSRQ_SERIAL=y Telcontar:~ # To try: You could try [Alt+Impr] +[?]. That should normally print out a helpful message on what system requests are availabe. It will log things to syslog. REISUB is the usual sequence of keys to "safely" reboot in an emergency. Notice that having the magic key enabled is a security risk if there are people around that can use it. -- Cheers / Saludos, Carlos E. R. (from 15.0 x86_64 at Telcontar)