Hi, I guess I found it! The kernel module files have to be present under /lib/modules inside the container, even when they are already loaded on the host side. After putting them there, everything works fine and I finally can record kernel events.
Thank you so much for your support. Regards Dirk On Thu, Nov 7, 2024 at 3:58 PM Dirk Eibach <dirk.eib...@googlemail.com> wrote: > > Hi Mathieu, > > > 1) You modprobe all LTTng modules from your top level namespace (host > > system) before starting lttng-sessiond within the container, or > > since I already did a lttng session on the host/top level namespacer > the modules are already loaded: > > root@9348eb19e6f4:/# lsmod > Module Size Used by > lttng_probe_x86_exceptions 16384 0 > lttng_probe_x86_irq_vectors 16384 0 > lttng_probe_workqueue 20480 0 > lttng_probe_vmscan 32768 0 > lttng_probe_udp 16384 0 > lttng_probe_timer 28672 0 > lttng_probe_sunrpc 20480 0 > lttng_probe_statedump 45056 0 > lttng_probe_sock 16384 0 > lttng_probe_skb 16384 0 > lttng_probe_signal 16384 0 > lttng_probe_scsi 20480 0 > lttng_probe_sched 40960 0 > lttng_probe_rcu 16384 0 > lttng_probe_printk 16384 0 > lttng_probe_power 20480 0 > lttng_probe_net 28672 0 > lttng_probe_napi 16384 0 > lttng_probe_module 20480 0 > lttng_probe_kvm 32768 0 > lttng_probe_kmem 28672 0 > lttng_probe_jbd2 28672 0 > lttng_probe_irq 16384 0 > lttng_probe_i2c 20480 0 > lttng_probe_ext4 155648 0 > lttng_probe_compaction 16384 0 > lttng_probe_btrfs 65536 0 > lttng_probe_block 36864 0 > lttng_counter_client_percpu_32_modular 16384 0 > lttng_counter_client_percpu_64_modular 16384 1 > lttng_counter 16384 2 > lttng_counter_client_percpu_64_modular,lttng_counter_client_percpu_32_modular > lttng_ring_buffer_event_notifier_client 16384 2 > lttng_ring_buffer_metadata_mmap_client 16384 0 > lttng_ring_buffer_client_mmap_overwrite 20480 0 > lttng_ring_buffer_client_mmap_discard 20480 0 > lttng_ring_buffer_metadata_client 16384 0 > lttng_ring_buffer_client_overwrite 20480 0 > lttng_ring_buffer_client_discard 20480 0 > lttng_tracer 2666496 40 > lttng_probe_udp,lttng_probe_scsi,lttng_probe_sched,lttng_probe_compaction,lttng_probe_net,lttng_probe_vmscan,lttng_probe_x86_irq_vectors,lttng_probe_power,lttng_probe_rcu,lttng_probe_module,lttng_ring_buffer_client_mmap_overwrite,lttng_probe_statedump,lttng_ring_buffer_client_discard,lttng_probe_printk,lttng_probe_x86_exceptions,lttng_probe_ext4,lttng_probe_sock,lttng_counter_client_percpu_64_modular,lttng_probe_irq,lttng_ring_buffer_client_mmap_discard,lttng_probe_kvm,lttng_probe_timer,lttng_probe_btrfs,lttng_ring_buffer_event_notifier_client,lttng_counter_client_percpu_32_modular,lttng_probe_workqueue,lttng_probe_jbd2,lttng_probe_i2c,lttng_probe_signal,lttng_probe_skb,lttng_probe_block,lttng_probe_napi,lttng_ring_buffer_metadata_client,lttng_probe_kmem,lttng_ring_buffer_metadata_mmap_client,lttng_ring_buffer_client_overwrite,lttng_probe_sunrpc > lttng_statedump 49152 1 lttng_tracer > lttng_wrapper 16384 7 > lttng_statedump,lttng_ring_buffer_client_mmap_overwrite,lttng_ring_buffer_client_discard,lttng_tracer,lttng_ring_buffer_client_mmap_discard,lttng_probe_kmem,lttng_ring_buffer_client_overwrite > lttng_clock 16384 5 > lttng_ring_buffer_client_mmap_overwrite,lttng_ring_buffer_client_discard,lttng_tracer,lttng_ring_buffer_client_mmap_discard,lttng_ring_buffer_client_overwrite > lttng_lib_ring_buffer 61440 8 > lttng_ring_buffer_client_mmap_overwrite,lttng_ring_buffer_client_discard,lttng_tracer,lttng_ring_buffer_client_mmap_discard,lttng_ring_buffer_event_notifier_client,lttng_ring_buffer_metadata_client,lttng_ring_buffer_metadata_mmap_client,lttng_ring_buffer_client_overwrite > > Thanks > Dirk > > On Thu, Nov 7, 2024 at 3:29 PM Mathieu Desnoyers > <mathieu.desnoy...@efficios.com> wrote: > > > > On 2024-11-07 03:03, Dirk Eibach via lttng-dev wrote: > > > Hi, > > > > > > sorry, Outlook is messing up my plaintext mails, so I am switching to > > > my gmail account. > > > > > >> lttng-modules exposes its control ABI through the virtual file > > >> /proc/lttng. > > >> > > >> Does you container have access to that file ? > > > > > > The container is running in privileged mode. > > > root@9348eb19e6f4:/# ls -l /proc/lttng > > > -rw------- 1 root root 0 Nov 6 16:05 /proc/lttng > > > > > >> Note that if you give access to that file within the container, then the > > >> container > > >> can observe detailed information about kernel internals (including > > >> related to > > >> other containers). > > > > > > This is a development-only system, so the security implications are > > > acceptable. > > > > > > I have observed one more thing. When I start the session daemon with > > > the -vvv option I get: > > > root@9348eb19e6f4:/# lttng list --kernel > > > DBG1 - 07:31:23.811796947 [Client management]: Wait for client > > > response (in thread_manage_clients() at client.c:2576) > > > DBG1 - 07:31:23.811867247 [Client management]: Receiving data from > > > client ... (in thread_manage_clients() at client.c:2604) > > > DBG1 - 07:31:23.811945247 [Client management]: Processing client > > > command 'LTTNG_LIST_TRACEPOINTS' (14) (in process_client_msg() at > > > client.c:1016) > > > Error: Failed to load kmod library resources > > > Warning: No kernel tracer available > > > > I suspect that you have two choices here: > > > > 1) You modprobe all LTTng modules from your top level namespace (host > > system) before starting lttng-sessiond within the container, or > > > > 2) You ensure that the container has the ability to load kernel > > modules, and you make sure the lttng-modules .ko are available > > in the container's under /lib/modules/$(uname -r)/ directory. > > (and run depmod -a), then launch lttng-sessiond as root. > > > > Thanks, > > > > Mathieu > > > > > DBG1 - 07:31:23.812076447 [Client management]: Missing llm header, > > > creating one. (in process_client_msg() at client.c:2381) > > > DBG1 - 07:31:23.812085547 [Client management]: Sending response (size: > > > 24, retcode: Kernel tracer not available (33)) (in > > > thread_manage_clients() at client.c:2683) > > > DBG1 - 07:31:23.812156547 [Client management]: Accepting client > > > command ... (in thread_manage_clients() at client.c:2534) > > > Error: Unable to list kernel events: Kernel tracer not available > > > > > > Regards > > > Dirk > > > > -- > > Mathieu Desnoyers > > EfficiOS Inc. > > https://www.efficios.com > >
