Bug 695283 – function_graph is not listed in /sys/kernel/debug/tracing/available_tracers, but /boot/config shows it as enabled

Bug 695283 - function_graph is not listed in /sys/kernel/debug/tracing/available_tracers, but /boot/config shows it as enabled

Summary:	function_graph is not listed in /sys/kernel/debug/tracing/available_tracers, ...

Status:	CLOSED NOTABUG

Aliases:	None

Product:	Fedora
Classification:	Fedora
Component:	kernel (Show other bugs)
Sub Component:
Version:	14
Hardware:	i686 Linux

Priority	unspecified Severity low
Target Milestone:	---
Target Release:	---
Assigned To:	Kernel Maintainer List
QA Contact:	Fedora Extras Quality Assurance
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Reported:	2011-04-11 06:22 EDT by Robin Green
Modified:	2011-04-12 11:54 EDT (History)
CC List:	6 users (show)

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Fixed In Version:
Doc Type:	Bug Fix
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Last Closed:	2011-04-12 11:54:00 EDT
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Description Robin Green 2011-04-11 06:22:00 EDT

Description of problem:
According to /boot/config-2.6.35.11-83.fc14.i686.PAE, function_graph tracing is configured:

CONFIG_HAVE_FUNCTION_GRAPH_TRACER=y

but it doesn't show up in /sys/kernel/debug/tracing/available_tracers

Version-Release number of selected component (if applicable):
kernel-PAE-2.6.35.11-83.fc14.i686

How reproducible:
Haven't tried

Steps to Reproduce:
1. Mount debugfs at /sys/kernel/debug
2. cat /sys/kernel/debug/tracing/available_tracers
  
Actual results:
ksym_tracer blk kmemtrace wakeup_rt wakeup function sysprof sched_switch nop

Expected results:
A list that includes function_graph

Additional info:
This problem was reported last year by someone else on LKML with a self-built kernel, but there were no replies on-list.

Comment 1 Robin Green 2011-04-12 11:54:00 EDT

It's not supported on x86 unless CC_OPTIMIZE_FOR_SIZE is disabled, which is enabled in the Fedora kernel.

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