Patch 2/2 adds a configurable handler to execute a compound action. Userland might want to execute e.g. 'w' (show blocked tasks), followed by 's' (sync), followed by 1000 ms delay and then followed by 'c' (crash) upon a single magic SysRq. Or one might want to execute the famous "Raising Elephants Is So Utterly Boring" action. This patch adds a configurable handler, triggered with 'C', for this exact purpose. The user specifies the composition of the compound action using syntax similar to getopt, where each letter corresponds to an individual action and a colon followed by a number corresponds to a delay of that many milliseconds, e.g.: ws:1000c or r:100eis:1000ub An example of userspace that wants to perform a compound action is Chrome OS, where SysRq-X (pressed for the second time within a certain time period from the first time) causes showing the locked tasks, syncing, waiting a 1000 ms delay and crashing the system. Since all the slots in the sysrq_key_table[] are already taken or reserved, patch 1/2 extends it to cover also capital letter versions. Andrzej Pietrasiewicz (2): tty/sysrq: Extend the sysrq_key_table to cover capital letters tty/sysrq: Add configurable handler to execute a compound action Documentation/admin-guide/sysrq.rst | 11 +++ drivers/tty/sysrq.c | 128 +++++++++++++++++++++++++++- include/linux/sysrq.h | 1 + 3 files changed, 138 insertions(+), 2 deletions(-) base-commit: bcf876870b95592b52519ed4aafcf9d95999bc9c -- 2.17.1
