Bug 85171

Summary: Hang on boot in 3.17+
Product: Drivers Reporter: brent s. (brent.saner)
Component: Video(DRI - Intel)Assignee: intel-gfx-bugs (intel-gfx-bugs)
Status: RESOLVED DUPLICATE    
Severity: blocking CC: aaron.lu, intel-gfx-bugs
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 3.17+ Subsystem:
Regression: Yes Bisected commit-id:
Bug Depends on:    
Bug Blocks: 84221    
Attachments: /sys/kernel/debug/dri/0/i915_opregion

Description brent s. 2014-09-26 07:09:54 UTC 
While trying a patch for Bug #84221, the kernel in 3.17 series hangs on boot.

The boot screen can be seen here: https://bugzilla.kernel.org/attachment.cgi?id=150961

dmidecode and lspci output are in but #84221.
Comment 1 Aaron Lu 2014-10-17 01:43:58 UTC 
Mark it as a regression according to brent: https://bugzilla.kernel.org/show_bug.cgi?id=84221#c27
Comment 2 brent s. 2014-10-23 10:17:38 UTC 
since nobody's apparently doing anything for this bug, which has now hit my distro's mainstream, i did a bit more troubleshooting.

it does not hang if i append the nomodeset kernel paramater, so it seems to me to be related to DR(I/M)/KMS. indeed, it hangs on the drmfb loading when i enable the "debug" kernel parameter.

(of course, then the resolutions for both the TTY and the graphical environment are a wonky horrible 640x480 or so)
Comment 3 Jani Nikula 2014-10-23 14:10:52 UTC 
Following a hunch, please attach /sys/kernel/debug/dri/0/i915_opregion.
Comment 4 Jani Nikula 2014-10-23 14:12:11 UTC 
Can be copied running any kernel.
Comment 5 brent s. 2014-10-23 15:00:32 UTC 
Created attachment 154671 [details]
/sys/kernel/debug/dri/0/i915_opregion
Comment 6 Jani Nikula 2014-10-23 16:22:25 UTC 
Hunch FTW. Thanks for the report, we're on this.

*** This bug has been marked as a duplicate of bug 86551 ***