Linux Kernel Markers for 2.6.23-rc8-mm2

Index: linux-2.6-lttng/arch/alpha/oprofile/Kconfig
===================================================================
@@ -1,23 +0,0 @@
-
-menu "Profiling support"
-	depends on EXPERIMENTAL
-
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-	  
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-endmenu
-

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Index: linux-2.6-lttng/arch/blackfin/oprofile/Kconfig
===================================================================
@@ -1,29 +0,0 @@
-menu "Profiling support"
-depends on EXPERIMENTAL
-
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-config HARDWARE_PM
-	tristate "Hardware Performance Monitor Profiling"
-	depends on PROFILING
-	help
-	  take use of hardware performance monitor to profiling the kernel
-	  and application.
-
-	  If unsure, say N.
-
-endmenu

Index: linux-2.6-lttng/arch/i386/oprofile/Kconfig
===================================================================
@@ -1,17 +0,0 @@
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-	  
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-

Index: linux-2.6-lttng/arch/ia64/oprofile/Kconfig
===================================================================
@@ -1,20 +0,0 @@
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  Due to firmware bugs, you may need to use the "nohalt" boot
-	  option if you're using OProfile with the hardware performance
-	  counters.
-
-	  If unsure, say N.
-

Index: linux-2.6-lttng/arch/m32r/oprofile/Kconfig
===================================================================
@@ -1,23 +0,0 @@
-
-menu "Profiling support"
-	depends on EXPERIMENTAL
-
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-endmenu
-

Index: linux-2.6-lttng/arch/mips/oprofile/Kconfig
===================================================================
@@ -1,23 +0,0 @@
-
-menu "Profiling support"
-	depends on EXPERIMENTAL
-
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING && !MIPS_MT_SMTC && EXPERIMENTAL
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-endmenu
-

Index: linux-2.6-lttng/arch/parisc/oprofile/Kconfig
===================================================================
@@ -1,23 +0,0 @@
-
-menu "Profiling support"
-	depends on EXPERIMENTAL
-
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-	  
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-endmenu
-

Index: linux-2.6-lttng/arch/powerpc/oprofile/Kconfig
===================================================================
@@ -1,24 +0,0 @@
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-config OPROFILE_CELL
-	bool "OProfile for Cell Broadband Engine"
-	depends on (SPU_FS = y && OPROFILE = m) || (SPU_FS = y && OPROFILE = y) || (SPU_FS = m && OPROFILE = m)
-	default y
-	help
-	  Profiling of Cell BE SPUs requires special support enabled
-	  by this option.

Index: linux-2.6-lttng/arch/s390/oprofile/Kconfig
===================================================================
@@ -1,22 +0,0 @@
-
-menu "Profiling support"
-
-config PROFILING
-	bool "Profiling support"
-	help
-	  Say Y here to enable profiling support mechanisms used by
-	  profilers such as readprofile or OProfile.
-
-
-config OPROFILE
-	tristate "OProfile system profiling"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-endmenu
-

Index: linux-2.6-lttng/arch/sh/oprofile/Kconfig
===================================================================
@@ -1,23 +0,0 @@
-
-menu "Profiling support"
-	depends on EXPERIMENTAL
-
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-	  
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-endmenu
-

Index: linux-2.6-lttng/arch/sh64/oprofile/Kconfig
===================================================================
@@ -1,23 +0,0 @@
-
-menu "Profiling support"
-	depends on EXPERIMENTAL
-
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-
-endmenu
-

Index: linux-2.6-lttng/arch/sparc/oprofile/Kconfig
===================================================================
@@ -1,17 +0,0 @@
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-	  
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-

Index: linux-2.6-lttng/arch/sparc64/oprofile/Kconfig
===================================================================
@@ -1,17 +0,0 @@
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-	  
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-

Index: linux-2.6-lttng/arch/x86_64/oprofile/Kconfig
===================================================================
@@ -1,17 +0,0 @@
-config PROFILING
-	bool "Profiling support (EXPERIMENTAL)"
-	help
-	  Say Y here to enable the extended profiling support mechanisms used
-	  by profilers such as OProfile.
-	  
-
-config OPROFILE
-	tristate "OProfile system profiling (EXPERIMENTAL)"
-	depends on PROFILING
-	help
-	  OProfile is a profiling system capable of profiling the
-	  whole system, include the kernel, kernel modules, libraries,
-	  and applications.
-
-	  If unsure, say N.
-

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Index: linux-2.6-lttng/arch/i386/Kconfig
===================================================================
@@ -1251,30 +1251,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-menuconfig INSTRUMENTATION
-	bool "Instrumentation Support"
-	default y
-	---help---
-	  Say Y here to get to see options related to performance measurement,
-	  debugging, and testing. This option alone does not add any kernel code.
-
-	  If you say N, all options in this submenu will be skipped and disabled.
-
-if INSTRUMENTATION
-
-source "arch/i386/oprofile/Kconfig"
-
-config KPROBES
-	bool "Kprobes"
-	depends on KALLSYMS && MODULES
-	help
-	  Kprobes allows you to trap at almost any kernel address and
-	  execute a callback function.  register_kprobe() establishes
-	  a probepoint and specifies the callback.  Kprobes is useful
-	  for kernel debugging, non-intrusive instrumentation and testing.
-	  If in doubt, say "N".
-
-endif # INSTRUMENTATION
+source "kernel/Kconfig.instrumentation"
 
 source "arch/i386/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/alpha/Kconfig
===================================================================
@@ -654,7 +654,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-source "arch/alpha/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 source "arch/alpha/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/arm/Kconfig
===================================================================
@@ -1061,7 +1061,7 @@ endmenu
 
 source "fs/Kconfig"
 
-source "arch/arm/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 source "arch/arm/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/blackfin/Kconfig
===================================================================
@@ -914,7 +914,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-source "arch/blackfin/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 menu "Kernel hacking"
 

Index: linux-2.6-lttng/arch/cris/Kconfig
===================================================================
@@ -196,6 +196,8 @@ source "sound/Kconfig"
 
 source "drivers/usb/Kconfig"
 
+source "kernel/Kconfig.instrumentation"
+
 source "arch/cris/Kconfig.debug"
 
 source "security/Kconfig"

Index: linux-2.6-lttng/arch/frv/Kconfig
===================================================================
@@ -375,6 +375,8 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
+source "kernel/Kconfig.instrumentation"
+
 source "arch/frv/Kconfig.debug"
 
 source "security/Kconfig"

Index: linux-2.6-lttng/arch/h8300/Kconfig
===================================================================
@@ -223,6 +223,8 @@ endmenu
 
 source "fs/Kconfig"
 
+source "kernel/Kconfig.instrumentation"
+
 source "arch/h8300/Kconfig.debug"
 
 source "security/Kconfig"

Index: linux-2.6-lttng/arch/ia64/Kconfig
===================================================================
@@ -582,20 +582,7 @@ config IRQ_PER_CPU
 
 source "arch/ia64/hp/sim/Kconfig"
 
-menu "Instrumentation Support"
-
-source "arch/ia64/oprofile/Kconfig"
-
-config KPROBES
-	bool "Kprobes"
-	depends on KALLSYMS && MODULES
-	help
-	  Kprobes allows you to trap at almost any kernel address and
-	  execute a callback function.  register_kprobe() establishes
-	  a probepoint and specifies the callback.  Kprobes is useful
-	  for kernel debugging, non-intrusive instrumentation and testing.
-	  If in doubt, say "N".
-endmenu
+source "kernel/Kconfig.instrumentation"
 
 source "arch/ia64/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/m32r/Kconfig
===================================================================
@@ -426,7 +426,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-source "arch/m32r/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 source "arch/m32r/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/m68k/Kconfig
===================================================================
@@ -683,6 +683,8 @@ endmenu
 
 source "fs/Kconfig"
 
+source "kernel/Kconfig.instrumentation"
+
 source "arch/m68k/Kconfig.debug"
 
 source "security/Kconfig"

Index: linux-2.6-lttng/arch/m68knommu/Kconfig
===================================================================
@@ -696,6 +696,8 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
+source "kernel/Kconfig.instrumentation"
+
 source "arch/m68knommu/Kconfig.debug"
 
 source "security/Kconfig"

Index: linux-2.6-lttng/arch/mips/Kconfig
===================================================================
@@ -1961,7 +1961,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-source "arch/mips/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 source "arch/mips/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/parisc/Kconfig
===================================================================
@@ -267,7 +267,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-source "arch/parisc/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 source "arch/parisc/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/powerpc/Kconfig
===================================================================
@@ -638,20 +638,7 @@ source "arch/powerpc/sysdev/qe_lib/Kconf
 
 source "lib/Kconfig"
 
-menu "Instrumentation Support"
-
-source "arch/powerpc/oprofile/Kconfig"
-
-config KPROBES
-	bool "Kprobes"
-	depends on !BOOKE && !4xx && KALLSYMS && MODULES
-	help
-	  Kprobes allows you to trap at almost any kernel address and
-	  execute a callback function.  register_kprobe() establishes
-	  a probepoint and specifies the callback.  Kprobes is useful
-	  for kernel debugging, non-intrusive instrumentation and testing.
-	  If in doubt, say "N".
-endmenu
+source "kernel/Kconfig.instrumentation"
 
 source "arch/powerpc/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/ppc/Kconfig
===================================================================
@@ -1307,7 +1307,7 @@ endmenu
 
 source "lib/Kconfig"
 
-source "arch/powerpc/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 source "arch/ppc/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/s390/Kconfig
===================================================================
@@ -529,21 +529,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-menu "Instrumentation Support"
-
-source "arch/s390/oprofile/Kconfig"
-
-config KPROBES
-	bool "Kprobes (EXPERIMENTAL)"
-	depends on EXPERIMENTAL && MODULES
-	help
-	  Kprobes allows you to trap at almost any kernel address and
-	  execute a callback function.	register_kprobe() establishes
-	  a probepoint and specifies the callback.  Kprobes is useful
-	  for kernel debugging, non-intrusive instrumentation and testing.
-	  If in doubt, say "N".
-
-endmenu
+source "kernel/Kconfig.instrumentation"
 
 source "arch/s390/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/sh/Kconfig
===================================================================
@@ -749,7 +749,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-source "arch/sh/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 source "arch/sh/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/sh64/Kconfig
===================================================================
@@ -285,7 +285,7 @@ source "drivers/Kconfig"
 
 source "fs/Kconfig"
 
-source "arch/sh64/oprofile/Kconfig"
+source "kernel/Kconfig.instrumentation"
 
 source "arch/sh64/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/sparc/Kconfig
===================================================================
@@ -320,11 +320,7 @@ endmenu
 
 source "fs/Kconfig"
 
-menu "Instrumentation Support"
-
-source "arch/sparc/oprofile/Kconfig"
-
-endmenu
+source "kernel/Kconfig.instrumentation"
 
 source "arch/sparc/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/sparc64/Kconfig
===================================================================
@@ -460,20 +460,7 @@ source "drivers/fc4/Kconfig"
 
 source "fs/Kconfig"
 
-menu "Instrumentation Support"
-
-source "arch/sparc64/oprofile/Kconfig"
-
-config KPROBES
-	bool "Kprobes (EXPERIMENTAL)"
-	depends on KALLSYMS && EXPERIMENTAL && MODULES
-	help
-	  Kprobes allows you to trap at almost any kernel address and
-	  execute a callback function.  register_kprobe() establishes
-	  a probepoint and specifies the callback.  Kprobes is useful
-	  for kernel debugging, non-intrusive instrumentation and testing.
-	  If in doubt, say "N".
-endmenu
+source "kernel/Kconfig.instrumentation"
 
 source "arch/sparc64/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/um/Kconfig
===================================================================
@@ -289,4 +289,6 @@ config INPUT
 	bool
 	default n
 
+source "kernel/Kconfig.instrumentation"
+
 source "arch/um/Kconfig.debug"

Index: linux-2.6-lttng/arch/v850/Kconfig
===================================================================
@@ -331,6 +331,8 @@ source "sound/Kconfig"
 
 source "drivers/usb/Kconfig"
 
+source "kernel/Kconfig.instrumentation"
+
 source "arch/v850/Kconfig.debug"
 
 source "security/Kconfig"

Index: linux-2.6-lttng/arch/x86_64/Kconfig
===================================================================
@@ -829,20 +829,7 @@ source "drivers/firmware/Kconfig"
 
 source fs/Kconfig
 
-menu "Instrumentation Support"
-
-source "arch/x86_64/oprofile/Kconfig"
-
-config KPROBES
-	bool "Kprobes"
-	depends on KALLSYMS && MODULES
-	help
-	  Kprobes allows you to trap at almost any kernel address and
-	  execute a callback function.  register_kprobe() establishes
-	  a probepoint and specifies the callback.  Kprobes is useful
-	  for kernel debugging, non-intrusive instrumentation and testing.
-	  If in doubt, say "N".
-endmenu
+source "kernel/Kconfig.instrumentation"
 
 source "arch/x86_64/Kconfig.debug"
 

Index: linux-2.6-lttng/arch/xtensa/Kconfig
===================================================================
@@ -251,6 +251,8 @@ config EMBEDDED_RAMDISK_IMAGE
 	  provide one yourself.
 endmenu
 
+source "kernel/Kconfig.instrumentation"
+
 source "arch/xtensa/Kconfig.debug"
 
 source "security/Kconfig"

Index: linux-2.6-lttng/kernel/Kconfig.instrumentation
===================================================================
@@ -40,4 +40,10 @@ config KPROBES
 	  for kernel debugging, non-intrusive instrumentation and testing.
 	  If in doubt, say "N".
 
+config MARKERS
+	bool "Activate markers"
+	help
+	  Place an empty function call at each marker site. Can be
+	  dynamically changed for a probe function.
+
 endif # INSTRUMENTATION

Index: linux-2.6-lttng/kernel/Makefile
===================================================================
@@ -61,6 +61,7 @@ obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
 obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
 obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
 obj-$(CONFIG_RESOURCE_COUNTERS) += res_counter.o
+obj-$(CONFIG_MARKERS) += marker.o
 
 ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <[email protected]>, the -fno-omit-frame-pointer is

Index: linux-2.6-lttng/Makefile
===================================================================
@@ -772,6 +772,9 @@ vmlinux: $(vmlinux-lds) $(vmlinux-init) 
 ifdef CONFIG_HEADERS_CHECK
 	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
 endif
+ifdef CONFIG_SAMPLES
+	$(Q)$(MAKE) $(build)=samples
+endif
 	$(call vmlinux-modpost)
 	$(call if_changed_rule,vmlinux__)
 	$(Q)rm -f .old_version

Index: linux-2.6-lttng/samples/Kconfig
===================================================================
@@ -0,0 +1,11 @@
+# samples/Kconfig
+
+menuconfig SAMPLES
+	bool "Sample kernel code"
+	help
+	  You can build and test sample kernel code here.
+
+if SAMPLES
+
+
+endif # SAMPLES

Index: linux-2.6-lttng/lib/Kconfig.debug
===================================================================
@@ -558,3 +558,5 @@ config FAULT_INJECTION_STACKTRACE_FILTER
 	  Provide stacktrace filter for fault-injection capabilities
 
 source "lib/Kconfig.kgdb"
+
+source "samples/Kconfig"

Index: linux-2.6-lttng/samples/markers/Makefile
===================================================================
@@ -0,0 +1,4 @@
+# builds the kprobes example kernel modules;
+# then to use one (as root):  insmod <module_name.ko>
+
+obj-$(CONFIG_SAMPLE_MARKERS) += probe-example.o marker-example.o

Index: linux-2.6-lttng/samples/Makefile
===================================================================
@@ -0,0 +1,3 @@
+# Makefile for Linux samples code
+
+obj-$(CONFIG_SAMPLES)	+= markers/

Index: linux-2.6-lttng/samples/Kconfig
===================================================================
@@ -7,5 +7,10 @@ menuconfig SAMPLES
 
 if SAMPLES
 
+config SAMPLE_MARKERS
+	tristate "Build markers examples -- loadable modules only"
+	depends on MARKERS && m
+	help
+	  This build markers example modules.
 
 endif # SAMPLES

Index: linux-2.6-lttng/Documentation/markers.txt
===================================================================
@@ -0,0 +1,81 @@
+ 	             Using the Linux Kernel Markers
+
+			    Mathieu Desnoyers
+
+
+This document introduces Linux Kernel Markers and their use. It provides
+examples of how to insert markers in the kernel and connect probe functions to
+them and provides some examples of probe functions.
+
+
+* Purpose of markers
+
+A marker placed in code provides a hook to call a function (probe) that you can
+provide at runtime. A marker can be "on" (a probe is connected to it) or "off"
+(no probe is attached). When a marker is "off" it has no effect, except for
+adding a tiny time penalty (checking a condition for a branch) and space
+penalty (adding a few bytes for the function call at the end of the
+instrumented function and adds a data structure in a separate section).  When a
+marker is "on", the function you provide is called each time the marker is
+executed, in the execution context of the caller. When the function provided
+ends its execution, it returns to the caller (continuing from the marker site).
+
+You can put markers at important locations in the code. Markers are
+lightweight hooks that can pass an arbitrary number of parameters,
+described in a printk-like format string, to the attached probe function.
+
+They can be used for tracing and performance accounting.
+
+
+* Usage
+
+In order to use the macro trace_mark, you should include linux/marker.h.
+
+#include <linux/marker.h>
+
+And,
+
+trace_mark(subsystem_event, "%d %s", someint, somestring);
+Where :
+- subsystem_event is an identifier unique to your event
+    - subsystem is the name of your subsystem.
+    - event is the name of the event to mark.
+- "%d %s" is the formatted string for the serializer.
+- someint is an integer.
+- somestring is a char pointer.
+
+Connecting a function (probe) to a marker is done by providing a probe (function
+to call) for the specific marker through marker_probe_register() and can be
+activated by calling marker_arm(). Marker deactivation can be done by calling
+marker_disarm() as many times as marker_arm() has been called. Removing a probe
+is done through marker_probe_unregister(); it will disarm the probe and make
+sure there is no caller left using the probe when it returns. Probe removal is
+preempt-safe because preemption is disabled around the probe call. See the
+"Probe example" section below for a sample probe module.
+
+The marker mechanism supports inserting multiple instances of the same marker.
+Markers can be put in inline functions, inlined static functions, and
+unrolled loops as well as regular functions.
+
+The naming scheme "subsystem_event" is suggested here as a convention intended
+to limit collisions. Marker names are global to the kernel: they are considered
+as being the same whether they are in the core kernel image or in modules.
+Conflicting format strings for markers with the same name will cause the markers
+to be detected to have a different format string not to be armed and will output
+a printk warning which identifies the inconsistency:
+
+"Format mismatch for probe probe_name (format), marker (format)"
+
+
+* Probe / marker example
+
+See the example provided in samples/markers/src
+
+Compile them with your kernel.
+
+Run, as root :
+modprobe marker-example (insmod order is not important)
+modprobe probe-example
+cat /proc/marker-example (returns an expected error)
+rmmod marker-example probe-example
+dmesg