Guys.
I am trying to study virtual memory management on Nexus 6P(An Old Android Smartphone)
Because the default kernel in AOSP didn't turn CONFIG_FUNCITON_TRACER on, and I can't use function tracer to study memory management related functions.
So I downloaded android kernel source code, turn on config_function_tracer and the other configs its depends, rebuilt kernel. Then I put the rebuilt kernel image file into aosp, rebuilt boot image , and flash the building output images into the phone.
the phone can boot normally, everything is ok but I can't 'cat /sys/kernel/debug/tracing/available_filter_functions' normally, it prompts "no such device".
I checked the selinux label, and I turn off the selinux by command 'setenforce permissive', it can't help.
can anyone help me to fix this problem?
C:\Users\dvdface>adb shellangler:/ # cd /sys/kernel/debug/tracing/angler:/sys/kernel/debug/tracing # lsREADME dyn_ftrace_total_info per_cpu set_ftrace_pid tracing_cpumaskavailable_events enabled_functions printk_formats set_graph_function tracing_onavailable_filter_functions events saved_cmdlines trace tracing_threshavailable_tracers free_buffer saved_tgids trace_clockbuffer_size_kb instances set_event trace_markerbuffer_total_size_kb max_graph_depth set_ftrace_filter trace_optionscurrent_tracer options set_ftrace_notrace trace_pipeangler:/sys/kernel/debug/tracing # cat available_filter_functionscat: available_filter_functions: No such device