* Mathieu Desnoyers ([email protected]) wrote: > * [email protected] ([email protected]) wrote: > > *** I'm resending this because I saw that mailman scrubbed my message.*** > > > > > > Mathieu: > > > > I have provided the requested information below. > > > > Also, I want to include some additional information which may (or may not) > > be part of the problem. When lttng-sessiond starts, I'm met with a > > modprobe error (see below). It looks as if this module is not being built > > at compile time because CONFIG_KVM is not enabled. However, if I go into > > the kernel menuconfig and search for KVM, no results are returned. > > Normally lttng-modules should use the features that are there without > complaining too much. > > What I notice is that you don't have CONFIG_HAVE_SYSCALL_TRACEPOINTS > enabled. So -k -a is enabling both tracepoints and syscalls, and given > that syscall enabling returns ENOSYS, it prints this error and bails > out. > > The correct behavior would be to only fail of _both_ tracepoint and > syscall instrumentation fail to enable. > > Short term solution for you would be to enable > CONFIG_HAVE_SYSCALL_TRACEPOINTS in your kernel.
FYI, here is the update. Feedback is welcome, commit d0a5ff7d8479de94f1082055d1d940d660027fc8 Author: Mathieu Desnoyers <[email protected]> Date: Fri Apr 6 12:32:22 2012 -0400 Fix: document required and optional kernel config options in README Signed-off-by: Mathieu Desnoyers <[email protected]> diff --git a/README b/README index abbfd27..ac0dc88 100644 --- a/README +++ b/README @@ -1,7 +1,7 @@ LTTng 2.0 modules Mathieu Desnoyers -February 8, 2012 +April 6, 2012 LTTng 2.0 kernel modules build against a vanilla or distribution kernel, without need for additional patches. Other features: @@ -48,9 +48,42 @@ LTTng 0.x patchset, but the lttng-modules 2.0 replace the lttng-modules 0.x, so both tracers cannot be installed at the same time for a given kernel version. -LTTng-modules depends on having kallsyms enabled in the kernel it is -built against. Ideally, if you want to have system call tracing, the -"Trace Syscalls" feature should be enabled too. + +* Kernel config options requied + +CONFIG_KALLSYMS: required + * See wrapper/ files. This is necessary until the few required missing + symbols are exported to GPL modules from mainline. +CONFIG_HIGH_RES_TIMERS: required + * Needed for LTTng 2.0 clock source. +CONFIG_TRACEPOINTS: required + kernel tracepoint instrumentation + * Enabled as side-effect of any of the perf/ftrace/blktrace + instrumentation features. + + +* Kernel config options supported (optional) + +The following kernel configuration options will affect the features +available from LTTng: + + +CONFIG_HAVE_SYSCALL_TRACEPOINTS: + system call tracing + lttng enable-event -k --syscall + lttng enable-event -k -a +CONFIG_PERF_EVENTS: + performance counters + lttng add-context -t perf:* +CONFIG_EVENT_TRACING: + needed to allow block layer tracing +CONFIG_KPROBES: + Dynamic probe. + lttng enable-event -k --probe ... +CONFIG_KRETPROBES: + Dynamic function entry/return probe. + lttng enable-event -k --function ... + * Note about Perf PMU counters support -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
