Bug 14485

Summary: System lockup running "cat /sys/kernel/debug/dri/0/i915_regs"
Product: Drivers Reporter: Rafael J. Wysocki (rjw)
Component: Video(DRI - Intel)Assignee: Jesse Barnes (jbarnes)
Status: CLOSED CODE_FIX    
Severity: high CC: gordon.jin, jbarnes, jcnengel, zhenyuw
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 2.6.32-rc5-git3 Subsystem:
Regression: Yes Bisected commit-id:
Bug Depends on:    
Bug Blocks: 14230    

Description Rafael J. Wysocki 2009-10-26 18:17:53 UTC 
Subject    : 2.6.32-rc5-git3 -- System lockup running "cat /sys/kernel/debug/dri/0/i915_regs"
Submitter  : Miles Lane <miles.lane@gmail.com>
Date       : 2009-10-26 4:00
References : http://marc.info/?l=linux-kernel&m=125652968117713&w=4

This entry is being used for tracking a regression from 2.6.31.  Please don't
close it until the problem is fixed in the mainline.
Comment 1 Jesse Barnes 2009-12-02 19:18:07 UTC 
Zhenyu, I think you mentioned you would fix this one?  I don't think it's a high prio since it's just a debug file, but hanging is pretty unfriendly.
Comment 2 zhenyuw 2009-12-28 03:55:38 UTC 
Sorry for missed this one for long time. I was thinking at lease we need to ask for explicitly enable all regs reading before actually doing so, but now I wonder who is the real user of this debug? If something really need that, we can do it totally in intel-gpu-tools instead of exposing this in kernel which is danger. 

So I think we should remove that completely.
Comment 3 zhenyuw 2010-01-08 04:51:16 UTC 
Patch is in Linus tree.
commit 823f68fd646da6a39a9c0d3eb4c60d69dab5aa13
Author: Zhenyu Wang <zhenyuw@linux.intel.com>
Date:   Mon Dec 28 13:23:36 2009 +0800

    drm/i915: remove full registers dump debug
    
    This one reverts 9e3a6d155ed0a7636b926a798dd7221ea107b274.
    As reported by http://bugzilla.kernel.org/show_bug.cgi?id=14485,
    this dump will cause hang problem on some machine. If something
    really needs this kind of full registers dump, that could be done
    within intel-gpu-tools.
    
    Cc: Ben Gamari <bgamari.foss@gmail.com>
    Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
    Signed-off-by: Eric Anholt <eric@anholt.net>
Comment 4 Jesse Barnes 2010-01-08 16:28:46 UTC 
Patch is upstream, closing.