Hi, I'm trying to enable Ftrace on my ARM based MMU-less system. Unexpectedly, I don't see tracing directory under /sys/kernel/debug I have done the following so far but no success: 1. Verified that I have enabled these flags in my .config CONFIG_FUNCTION_TRACER CONFIG_FUNCTION_GRAPH_TRACER CONFIG_STACK_TRACER CONFIG_DYNAMIC_FTRACE
2. Enabled Ftrace startup steps. The startup log output is ---- <...> ftrace: allocating 8996 entries in 27 pages Testing tracer nop: PASSED <...> Testing tracer function: PASSED Testing dynamic ftrace: PASSED Testing dynamic ftrace ops #1: (1 0 1 1 0) (1 1 2 1 0) (2 1 3 1 2) (2 2 4 1 59) PASSED Testing dynamic ftrace ops #2: (1 0 1 2 0) (1 1 2 59 0) (2 1 3 1 2) (2 2 4 58 59) PASSED Testing tracer function_graph: PASSED <..> Running tests on trace events: Testing event snd_soc_reg_write: OK Testing event snd_soc_reg_read: OK Testing event snd_soc_preg_write: OK Testing event snd_soc_preg_read: OK Testing event snd_soc_bias_level_start: OK Testing event snd_soc_bias_level_done: OK Testing event snd_soc_dapm_start: OK Testing event snd_soc_dapm_done: OK Testing event snd_soc_dapm_widget_power: OK Testing event snd_soc_dapm_widget_event_start: OK Testing event snd_soc_dapm_widget_event_done: OK Testing event snd_soc_dapm_walk_done: OK Testing event snd_soc_jack_irq: OK Testing event snd_soc_jack_report: OK Testing event snd_soc_jack_notify: OK Testing event snd_soc_cache_sync: OK Testing event scsi_dispatch_cmd_start: OK Testing event scsi_dispatch_cmd_error: OK Testing event scsi_dispatch_cmd_done: OK Testing event scsi_dispatch_cmd_timeout: OK Testing event scsi_eh_wakeup: OK Testing event regmap_reg_write: OK Testing event regmap_reg_read: OK Testing event regmap_reg_read_cache: OK Testing event regmap_hw_read_start: OK Testing event regmap_hw_read_done: OK Testing event regmap_hw_write_start: OK Testing event regmap_hw_write_done: OK Testing event regcache_sync: OK Testing event gpio_direction: OK Testing event gpio_value: OK Testing event block_rq_abort: OK Testing event block_rq_requeue: OK Testing event block_rq_complete: OK Testing event block_rq_insert: OK Testing event block_rq_issue: OK Testing event block_bio_bounce: OK Testing event block_bio_complete: OK Testing event block_bio_backmerge: OK Testing event block_bio_frontmerge: OK Testing event block_bio_queue: OK Testing event block_getrq: OK Testing event block_sleeprq: OK Testing event block_plug: OK Testing event block_unplug: OK Testing event block_split: OK Testing event block_bio_remap: OK Testing event block_rq_remap: OK Testing event writeback_nothread: OK Testing event writeback_queue: OK Testing event writeback_exec: OK Testing event writeback_start: OK Testing event writeback_written: OK Testing event writeback_wait: OK Testing event writeback_pages_written: OK Testing event writeback_nowork: OK Testing event writeback_wake_background: OK Testing event writeback_wake_thread: OK Testing event writeback_wake_forker_thread: OK Testing event writeback_bdi_register: OK Testing event writeback_bdi_unregister: OK Testing event writeback_thread_start: OK Testing event writeback_thread_stop: OK Testing event wbc_writepage: OK Testing event writeback_queue_io: OK Testing event global_dirty_state: OK Testing event bdi_dirty_ratelimit: OK Testing event balance_dirty_pages: OK Testing event writeback_congestion_wait: OK Testing event writeback_wait_iff_congested: OK Testing event writeback_single_inode_requeue: OK Testing event writeback_single_inode: OK Testing event kmalloc: OK Testing event kmem_cache_alloc: OK Testing event kmalloc_node: OK Testing event kmem_cache_alloc_node: OK Testing event kfree: OK Testing event kmem_cache_free: OK Testing event mm_page_free: OK Testing event mm_page_free_batched: OK Testing event mm_page_alloc: OK Testing event mm_page_alloc_zone_locked: OK Testing event mm_page_pcpu_drain: OK Testing event mm_page_alloc_extfrag: OK Testing event mm_vmscan_kswapd_sleep: OK Testing event mm_vmscan_kswapd_wake: OK Testing event mm_vmscan_wakeup_kswapd: OK Testing event mm_vmscan_direct_reclaim_begin: OK Testing event mm_vmscan_memcg_reclaim_begin: OK Testing event mm_vmscan_memcg_softlimit_reclaim_begin: OK Testing event mm_vmscan_direct_reclaim_end: OK Testing event mm_vmscan_memcg_reclaim_end: OK Testing event mm_vmscan_memcg_softlimit_reclaim_end: OK Testing event mm_shrink_slab_start: OK Testing event mm_shrink_slab_end: OK Testing event mm_vmscan_lru_isolate: OK Testing event mm_vmscan_memcg_isolate: OK Testing event mm_vmscan_writepage: OK Testing event mm_vmscan_lru_shrink_inactive: OK Testing event replace_swap_token: OK Testing event put_swap_token: OK Testing event disable_swap_token: OK Testing event update_swap_token_priority: OK Testing event oom_score_adj_update: OK Testing event cpu_idle: OK Testing event cpu_frequency: OK Testing event machine_suspend: OK Testing event power_start: OK Testing event power_frequency: OK Testing event power_end: OK Testing event clock_enable: OK Testing event clock_disable: OK Testing event clock_set_rate: OK Testing event power_domain_target: OK Testing event ftrace_test_filter: OK Testing event module_load: OK Testing event module_free: OK Testing event module_get: OK Testing event module_put: OK Testing event module_request: OK Testing event sched_kthread_stop: OK Testing event sched_kthread_stop_ret: OK Testing event sched_wakeup: OK Testing event sched_wakeup_new: OK Testing event sched_switch: OK Testing event sched_migrate_task: OK Testing event sched_process_free: OK Testing event sched_process_exit: OK Testing event sched_wait_task: OK Testing event sched_process_wait: OK Testing event sched_process_fork: OK Testing event sched_stat_wait: OK Testing event sched_stat_sleep: OK Testing event sched_stat_iowait: OK Testing event sched_stat_blocked: OK Testing event sched_stat_runtime: OK Testing event sched_stat_sleeptime: OK Testing event sched_pi_setprio: OK Testing event rcu_utilization: OK Testing event workqueue_queue_work: OK Testing event workqueue_activate_work: OK Testing event workqueue_execute_start: OK Testing event workqueue_execute_end: OK Testing event signal_generate: OK Testing event signal_deliver: OK Testing event signal_overflow_fail: OK Testing event signal_lose_info: OK Testing event timer_init: OK Testing event timer_start: OK Testing event timer_expire_entry: OK Testing event timer_expire_exit: OK Testing event timer_cancel: OK Testing event hrtimer_init: OK Testing event hrtimer_start: OK Testing event hrtimer_expire_entry: OK Testing event hrtimer_expire_exit: OK Testing event hrtimer_cancel: OK Testing event itimer_state: OK Testing event itimer_expire: OK Testing event irq_handler_entry: OK Testing event irq_handler_exit: OK Testing event softirq_entry: OK Testing event softirq_exit: OK Testing event softirq_raise: OK Testing event task_newtask: OK Testing event task_rename: OK Running tests on trace event systems: Testing event system asoc: OK Testing event system scsi: OK Testing event system regmap: OK Testing event system gpio: OK Testing event system block: OK Testing event system writeback: OK Testing event system kmem: OK Testing event system vmscan: OK Testing event system oom: OK Testing event system power: OK Testing event system test: OK Testing event system module: OK Testing event system sched: OK Testing event system rcu: OK Testing event system workqueue: OK Testing event system signal: OK Testing event system timer: OK Testing event system irq: OK Testing event system task: OK Running tests on all trace events: Testing all events: OK Running tests again, along with the function tracer Running tests on trace events: Testing event snd_soc_reg_write: OK Testing event snd_soc_reg_read: OK Testing event snd_soc_preg_write: OK Testing event snd_soc_preg_read: OK Testing event snd_soc_bias_level_start: OK Testing event snd_soc_bias_level_done: OK Testing event snd_soc_dapm_start: OK Testing event snd_soc_dapm_done: OK Testing event snd_soc_dapm_widget_power: OK Testing event snd_soc_dapm_widget_event_start: OK Testing event snd_soc_dapm_widget_event_done: OK Testing event snd_soc_dapm_walk_done: OK Testing event snd_soc_jack_irq: OK Testing event snd_soc_jack_report: OK Testing event snd_soc_jack_notify: OK Testing event snd_soc_cache_sync: OK Testing event scsi_dispatch_cmd_start: OK Testing event scsi_dispatch_cmd_error: OK Testing event scsi_dispatch_cmd_done: OK Testing event scsi_dispatch_cmd_timeout: OK Testing event scsi_eh_wakeup: OK Testing event regmap_reg_write: OK Testing event regmap_reg_read: OK Testing event regmap_reg_read_cache: OK Testing event regmap_hw_read_start: OK Testing event regmap_hw_read_done: OK Testing event regmap_hw_write_start: OK Testing event regmap_hw_write_done: OK Testing event regcache_sync: OK Testing event gpio_direction: OK Testing event gpio_value: OK Testing event block_rq_abort: OK Testing event block_rq_requeue: OK Testing event block_rq_complete: OK Testing event block_rq_insert: OK Testing event block_rq_issue: OK Testing event block_bio_bounce: OK Testing event block_bio_complete: OK Testing event block_bio_backmerge: OK Testing event block_bio_frontmerge: OK Testing event block_bio_queue: OK Testing event block_getrq: OK Testing event block_sleeprq: OK Testing event block_plug: OK Testing event block_unplug: OK Testing event block_split: OK Testing event block_bio_remap: OK Testing event block_rq_remap: OK Testing event writeback_nothread: OK Testing event writeback_queue: OK Testing event writeback_exec: OK Testing event writeback_start: OK Testing event writeback_written: OK Testing event writeback_wait: OK Testing event writeback_pages_written: OK Testing event writeback_nowork: OK Testing event writeback_wake_background: OK Testing event writeback_wake_thread: OK Testing event writeback_wake_forker_thread: OK Testing event writeback_bdi_register: OK Testing event writeback_bdi_unregister: OK Testing event writeback_thread_start: OK Testing event writeback_thread_stop: OK Testing event wbc_writepage: OK Testing event writeback_queue_io: OK Testing event global_dirty_state: OK Testing event bdi_dirty_ratelimit: OK Testing event balance_dirty_pages: OK Testing event writeback_congestion_wait: OK Testing event writeback_wait_iff_congested: OK Testing event writeback_single_inode_requeue: OK Testing event writeback_single_inode: OK Testing event kmalloc: OK Testing event kmem_cache_alloc: OK Testing event kmalloc_node: OK Testing event kmem_cache_alloc_node: OK Testing event kfree: OK Testing event kmem_cache_free: OK Testing event mm_page_free: OK Testing event mm_page_free_batched: OK Testing event mm_page_alloc: OK Testing event mm_page_alloc_zone_locked: OK Testing event mm_page_pcpu_drain: OK Testing event mm_page_alloc_extfrag: OK Testing event mm_vmscan_kswapd_sleep: OK Testing event mm_vmscan_kswapd_wake: OK Testing event mm_vmscan_wakeup_kswapd: OK Testing event mm_vmscan_direct_reclaim_begin: OK Testing event mm_vmscan_memcg_reclaim_begin: OK Testing event mm_vmscan_memcg_softlimit_reclaim_begin: OK Testing event mm_vmscan_direct_reclaim_end: OK Testing event mm_vmscan_memcg_reclaim_end: OK Testing event mm_vmscan_memcg_softlimit_reclaim_end: OK Testing event mm_shrink_slab_start: OK Testing event mm_shrink_slab_end: OK Testing event mm_vmscan_lru_isolate: OK Testing event mm_vmscan_memcg_isolate: OK Testing event mm_vmscan_writepage: OK Testing event mm_vmscan_lru_shrink_inactive: OK Testing event replace_swap_token: OK Testing event put_swap_token: OK Testing event disable_swap_token: OK Testing event update_swap_token_priority: OK Testing event oom_score_adj_update: OK Testing event cpu_idle: OK Testing event cpu_frequency: OK Testing event machine_suspend: OK Testing event power_start: OK Testing event power_frequency: OK Testing event power_end: OK Testing event clock_enable: OK Testing event clock_disable: OK Testing event clock_set_rate: OK Testing event power_domain_target: OK Testing event ftrace_test_filter: OK Testing event module_load: OK Testing event module_free: OK Testing event module_get: OK Testing event module_put: OK Testing event module_request: OK Testing event sched_kthread_stop: OK Testing event sched_kthread_stop_ret: OK Testing event sched_wakeup: OK Testing event sched_wakeup_new: OK Testing event sched_switch: OK Testing event sched_migrate_task: OK Testing event sched_process_free: OK Testing event sched_process_exit: OK Testing event sched_wait_task: OK Testing event sched_process_wait: OK Testing event sched_process_fork: OK Testing event sched_stat_wait: OK Testing event sched_stat_sleep: OK Testing event sched_stat_iowait: OK Testing event sched_stat_blocked: OK Testing event sched_stat_runtime: OK Testing event sched_stat_sleeptime: OK Testing event sched_pi_setprio: OK Testing event rcu_utilization: OK Testing event workqueue_queue_work: OK Testing event workqueue_activate_work: OK Testing event workqueue_execute_start: OK Testing event workqueue_execute_end: OK Testing event signal_generate: OK Testing event signal_deliver: OK Testing event signal_overflow_fail: OK Testing event signal_lose_info: OK Testing event timer_init: OK Testing event timer_start: OK Testing event timer_expire_entry: OK Testing event timer_expire_exit: OK Testing event timer_cancel: OK Testing event hrtimer_init: OK Testing event hrtimer_start: OK Testing event hrtimer_expire_entry: OK Testing event hrtimer_expire_exit: OK Testing event hrtimer_cancel: OK Testing event itimer_state: OK Testing event itimer_expire: OK Testing event irq_handler_entry: OK Testing event irq_handler_exit: OK Testing event softirq_entry: OK Testing event softirq_exit: OK Testing event softirq_raise: OK Testing event task_newtask: OK Testing event task_rename: OK Running tests on trace event systems: Testing event system asoc: OK Testing event system scsi: OK Testing event system regmap: OK Testing event system gpio: OK Testing event system block: OK Testing event system writeback: OK Testing event system kmem: OK Testing event system vmscan: OK Testing event system oom: OK Testing event system power: OK Testing event system test: OK Testing event system module: OK Testing event system sched: OK Testing event system rcu: OK Testing event system workqueue: OK Testing event system signal: OK Testing event system timer: OK Testing event system irq: OK Testing event system task: OK Running tests on all trace events: Testing all events: OK Testing ftrace filter: OK --- 3. The output of /proc/sys/kernel/ftrace_enabled is 1. Can anyone help what I'm missing or if ftrace is supported on MMU-less platforms? Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/