Version 2.5.6

[lttng-modules.git] / README

diff --git a/README b/README
index abbfd27746926f6a1426e81ee96b1c4c9e53a4e3..70d991f4d907024fa7d9390e60de25e566ba9aa9 100644 (file)
--- a/README
+++ b/README
@@ -1,9 +1,9 @@
-LTTng 2.0 modules
+LTTng 2.x modules
 
 Mathieu Desnoyers
-February 8, 2012
+March 29, 2013
 
-LTTng 2.0 kernel modules build against a vanilla or distribution kernel, without
+LTTng 2.x kernel modules build against a vanilla or distribution kernel, without
 need for additional patches. Other features:
 
 - Produces CTF (Common Trace Format) natively,
@@ -36,21 +36,48 @@ the kernel modules when needed. Use Babeltrace to print traces as a
 human-readable text log. These tools are available at the following URL:
 http://lttng.org/lttng2.0
 
-So far, it has been tested on vanilla Linux kernels 2.6.38, 2.6.39, 3.0,
-3.1, 3.2, 3.3 (on x86 32/64-bit, and powerpc 32-bit at the moment, build
-tested on ARM). It should work fine with newer kernels and other
-architectures, but expect build issues with kernels older than 2.6.36.
-The clock source currently used is the standard gettimeofday (slower,
-less scalable and less precise than the LTTng 0.x clocks).  Support for
-LTTng 0.x clocks will be added back soon into LTTng 2.0.  Please note
-that lttng-modules 2.0 can build on a Linux kernel patched with the
-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. 
+Linux kernels >= 2.6.36 are supported.
+
+
+* Kernel config options required
+
+CONFIG_MODULES: required
+  * Kernel modules support.
+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 ...
+CONFIG_KALLSYMS_ALL:
+            State dump of mapping between block device number and name.
+
 
 * Note about Perf PMU counters support