On Wed, 29 Jul 2026 13:32:32 -0400 Steven Rostedt <[email protected]> wrote:
> Honestly, I don't know of any tooling that would use this kill-switch or > any reason to do so. For live kernel patching and for BPF, it doesn't even > work. Hasn't for some time. It's now a "kill some ftrace but not all". > > Hence, again, the switch itself is rather useless. Also, since the BPF direct trampolines originally had the PERMANENT flag set, but due to some code updates lost the flag, and if someone were to turn off ftrace, it would cause bugs with the BPF programs that were using it, it makes me feel more confident that nothing is using that file to disable ftrace. The bug causing BPF programs being disabled by it has been around since 6.0 and there hasn't been any complaints about those BPF programs breaking. It makes me think there hasn't been tooling that set ftrace_disabled to zero! [ Distros now use BPF with ftrace cat /sys/kernel/tracing/enabled_functions to see if yours is too ] -- Steve
