Bug 439619

Summary: ppc kernel hardware watchpoint support
Product: [Fedora] Fedora Reporter: Jan Kratochvil <jan.kratochvil>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED CURRENTRELEASE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: low Docs Contact:
Priority: low    
Version: 8CC: luisgpm, roland
Target Milestone: ---   
Target Release: ---   
Hardware: ppc64   
OS: Linux   
URL: http://ozlabs.org/pipermail/linuxppc-dev/2007-November/thread.html#46951
Whiteboard:
Fixed In Version: 2.6.24.5-85.fc8 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2008-04-29 20:54:54 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 437970, 444076    
Bug Blocks:    
Attachments:
Description Flags
Upstream fix. none

Description Jan Kratochvil 2008-03-29 17:33:11 UTC 
+++ This bug was initially created as a clone of Bug #437970 +++

Description of problem:
There was a request to support hardware watchpoints (such as being used by GDB).

Version-Release number of selected component (if applicable):
It is a fresh upstream fix, so far all the kernel ppc/ppc64 variants had it broken.

How reproducible:
99% of runs with enough (>16) threads (set by THREADS).

Steps to Reproduce:
1. wget -O ppc-dabr-race.c
'http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/ppc-dabr-race.c?cvsroot=systemtap'
2. gcc -o ppc-dabr-race ppc-dabr-race.c -Wall -ggdb2 -m32 -D_GNU_SOURCE -pthread
3. ./ppc-dabr-race ;echo $?

Actual results:
1
Tested on: ppc03.englab.brq.redhat.com
kernel-2.6.25-0.121.rc5.git4.fc9.ppc64
Dual:
cpu             : POWER5 (gr)
clock           : 1502.496000MHz
revision        : 2.2 (pvr 003a 0202)

Expected results:
0

Additional info:
Compile with -DDEBUG to see why it fails.
It was discussed upstream with IBM, mail threads at:
  http://ozlabs.org/pipermail/linuxppc-dev/2007-November/thread.html#46951
  http://ozlabs.org/pipermail/linuxppc-dev/2008-March/thread.html#52788

-m64 has the same error as -m32.

Return code 77 means the kernel/CPU combo does not support hardware watchpoints.

-- Additional comment from roland on 2008-03-28 17:40 EST --
See upstream commit a2ceff5e555e664751bc653a4d9b133efa18c742,
seems to have fixed it.
Comment 1 Jan Kratochvil 2008-03-29 17:33:11 UTC 
Created attachment 299587 [details]
Upstream fix.
Comment 2 Dave Jones 2008-03-29 17:53:49 UTC 
added to cvs, will be in next build.
Comment 3 Fedora Update System 2008-04-22 00:04:42 UTC 
kernel-2.6.24.5-85.fc8 has been submitted as an update for Fedora 8
Comment 4 Fedora Update System 2008-04-22 22:43:10 UTC 
kernel-2.6.24.5-85.fc8 has been pushed to the Fedora 8 testing repository.  If problems still persist, please make note of it in this bug report.
 If you want to test the update, you can install it with 
 su -c 'yum --enablerepo=updates-testing update kernel'.  You can provide feedback for this update here: http://admin.fedoraproject.org/updates/F8/FEDORA-2008-3260
Comment 5 Fedora Update System 2008-04-29 20:54:32 UTC 
kernel-2.6.24.5-85.fc8 has been pushed to the Fedora 8 stable repository.  If problems still persist, please make note of it in this bug report.