[lttng-dev] Kernel tracer not available with lttng compiled in

[Jonathan Rajotte-Julien]

Hi,

We will need more information.

What version of lttng are we speaking of here?

What kernel version/tree?

Exactly how did you build your kernel with lttng-modules built-in?

Did you follow this?:

  https://github.com/lttng/lttng-modules/blob/master/README.md#kernel-built-in-support

Cheers

On Thu, Sep 05, 2019 at 12:23:40PM +0000, Kjeld Flarup via lttng-dev wrote:
> Hello 
> 
> I'm trying to get lttng working on an Power PC board
> 
> 
> ~ # lttng create my-kernel-session --output=/tmp/my-kernel-trace
> Spawning a session daemon
> Session my-kernel-session created.
> Traces will be written in /tmp/my-kernel-trace
> ~ # lttng list --kernel
> Error: Unable to list kernel events: Kernel tracer not available
> Error: Command error
> 
> Now ALL that I can find when googling this error is that the kernel modules is not loaded. 
> However I'm not using modules, but compile everything in. 
> 
> Here is a small extract of what is enabled in my kernel. I have attached the full /proc/config.gz
> Am I missing something?
> 
> CONFIG_NOP_TRACER=y
> CONFIG_HAVE_FUNCTION_TRACER=y
> CONFIG_HAVE_FUNCTION_GRAPH_TRACER=y
> CONFIG_TRACER_MAX_TRACE=y
> CONFIG_CONTEXT_SWITCH_TRACER=y
> CONFIG_GENERIC_TRACER=y
> CONFIG_FUNCTION_TRACER=y
> CONFIG_FUNCTION_GRAPH_TRACER=y
> CONFIG_IRQSOFF_TRACER=y
> CONFIG_PREEMPT_TRACER=y
> CONFIG_SCHED_TRACER=y
> # CONFIG_HWLAT_TRACER is not set
> CONFIG_TRACER_SNAPSHOT=y
> CONFIG_TRACER_SNAPSHOT_PER_CPU_SWAP=y
> # CONFIG_STACK_TRACER is not set
> 
> CONFIG_HAVE_KPROBES_ON_FTRACE=y
> CONFIG_HAVE_DYNAMIC_FTRACE=y
> CONFIG_HAVE_FTRACE_MCOUNT_RECORD=y
> CONFIG_FTRACE=y
> CONFIG_FTRACE_SYSCALLS=y
> CONFIG_DYNAMIC_FTRACE=y
> CONFIG_FTRACE_MCOUNT_RECORD=y
> # CONFIG_FTRACE_STARTUP_TEST is not set
> 
> 
> CONFIG_EVENT_TRACING=y
> CONFIG_PERF_EVENTS=y
> CONFIG_HAVE_SYSCALL_TRACEPOINTS=y
> 
> CONFIG_KRETPROBES=y
> 
> CONFIG_HIGH_RES_TIMERS=y
> CONFIG_TRACEPOINTS=y
> CONFIG_TRACE_IRQFLAGS_SUPPORT=y
> # CONFIG_TRACE_SINK is not set
> CONFIG_TRACE_IRQFLAGS=y
> CONFIG_TRACE_CLOCK=y
> CONFIG_TRACE_PREEMPT_TOGGLE=y
> CONFIG_TRACER_SNAPSHOT=y
> CONFIG_TRACER_SNAPSHOT_PER_CPU_SWAP=y
> # CONFIG_TRACEPOINT_BENCHMARK is not set
> # CONFIG_TRACE_EVAL_MAP_FILE is not set
> CONFIG_KALLSYMS=y
> # CONFIG_KALLSYMS_ALL is not set
> CONFIG_KALLSYMS_BASE_RELATIVE=y
> 
> 
> 
> Regards
> Kjeld Flarup
> DEIF A/S, R&D Platform Software
> 
> 


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-- 
Jonathan Rajotte-Julien
EfficiOS