Bug 113351

Summary: i7-6500U CPU on Thinkpad X1 Yoga does not boot without intel_pstate=no_hwp
Product: Power Management Reporter: Mario Geiger (geiger.mario)
Component: intel_pstateAssignee: Chen Yu (yu.c.chen)
Severity: normal CC: jacek, kernel.org, lenb, lubko+kernel, rui.zhang, srinivas.pandruvada, yu.c.chen
Priority: P1    
Hardware: Intel   
OS: Linux   
Kernel Version: 4.4 Tree: Mainline
Regression: No

Description Mario Geiger 2016-02-27 22:51:04 UTC
Does not boot until I put GRUB_CMDLINE_LINUX="intel_pstate=no_hwp" for grub parameter.
Comment 1 Jacek Bajor 2016-02-28 13:43:31 UTC
I am experiencing the same issue with kernel 4.5.0.rc4.
Comment 2 Chen Yu 2016-02-29 02:42:06 UTC
could you please test with:
boot kernel with intel_pstate=no_hwp

# modprobe msr

# rdmsr 0x770
# wrmsr 0x773 0
# rdmsr 0x773

# wrmsr ox770 1 

does it hang?

I suspect this is related to 
Comment 3 Jacek Bajor 2016-02-29 12:59:35 UTC
The machine did not hang right after executing command, but froze completely a minute later when I pressed the mute button.
Comment 4 Mario Geiger 2016-02-29 13:38:55 UTC
# modprobe msr
# rdmsr 0x770
# wrmsr 0x773 0
# rdmsr 0x773
# wrmsr 0x770 1 
[hang immediately]
Comment 5 Srinivas Pandruvada 2016-03-01 17:16:52 UTC
Can you try to boot with idle=nomwait and see if you can boot (without intel_pstate=no_hwp or intel_pstate=disable)?
Comment 6 Jacek Bajor 2016-03-02 00:11:12 UTC
I could not boot with idle=nomwait option.
Comment 7 Lubko 2016-03-09 10:27:04 UTC
most likely a duplicate of #110941
Comment 8 Chen Yu 2016-03-15 06:54:10 UTC

*** This bug has been marked as a duplicate of bug 110941 ***