Bug 504374

Summary: kvm: hw DR_* watchpoint registers are ignored
Product: [Fedora] Fedora Reporter: Jan Kratochvil <jan.kratochvil>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED RAWHIDE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: rawhideCC: berrange, clalance, ehabkost, gcosta, itamar, kernel-maint, markmc, onestero, quintela, roland, virt-maint
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: kernel-2.6.30-0.97.rc8.fc12.x86_64 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2009-06-08 14:28:31 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:    
Bug Blocks: 498969    

Description Jan Kratochvil 2009-06-05 20:33:53 UTC 
Description of problem:
GDB watchpoints do not work.  There is a standalone testcase for it.

Version-Release number of selected component (if applicable):
longterm, it never worked, verified on:
kernel-2.6.29.3-155.fc11.x86_64 (both as KVM host and guest)

How reproducible:
Always.

Steps to Reproduce:
wget -q -O watchpoint.c 'http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/watchpoint.c?cvsroot=systemtap'; gcc -Wall -g -o watchpoint watchpoint.c; ./watchpoint; echo $?

Actual results:
2

Expected results:
0

Additional info:
Return code 2 means the testcase missed the watchpoint to be hit.
Comment 1 Mark McLoughlin 2009-06-08 11:54:27 UTC 
Could you re-test with 2.6.30 from rawhide?

This was merged in 2.6.30-rc1:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=42dbaa5a05
Comment 2 Jan Kratochvil 2009-06-08 14:28:31 UTC 
Tested this version-in-KVM-on-version and it is now already working, thanks for the pointer:
kernel-2.6.30-0.97.rc8.fc12.x86_64