Bug 1353586

Summary:	Kernel no longer boots, freezes instantly after showing black screen with text cursor in corner
Product:	[Fedora] Fedora	Reporter:	ell1e <el>
Component:	kernel	Assignee:	Kernel Maintainer List <kernel-maint>
Status:	CLOSED DUPLICATE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	urgent	Docs Contact:
Priority:	unspecified
Version:	24	CC:	el, gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda, mchehab
Target Milestone:	---
Target Release:	---
Hardware:	x86_64
OS:	Linux
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Clone Of:		Environment:
Last Closed:	2016-07-07 15:38:45 UTC	Type:	Bug
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Embargoed:

Description ell1e 2016-07-07 13:43:11 UTC

Description of problem:
After upgrading from 4.5.5 to 4.6.3, this laptop no longer boots.
I can choose the kernel from grub, the screen goes black and a text cursor
shows in the upper left corner, and then it just freezes (nothing happens).
The proper graphical boot screen never shows.
I tried removing "quiet" and adding "DEBUG", but that didn't show anything helpful either.

Please note that this machine is affected by 
https://bugzilla.kernel.org/show_bug.cgi?id=110941
so that 4.5.5 only boots with intel_hwp=no_hwp.
However, 4.6.3 no longer boots at all no matter if that option is specified or not.

Version-Release number of selected component (if applicable):
4.6.3-300.fc24, x86_64

How reproducible:
100%

Steps to Reproduce:
1. Install Fedora 24 fresh from Live CD (Workstation variant) _WITHOUT_ internet/network access
2. Reboot into installed system (you will need to edit the grub command line and add intel_pstate=no_hwp for the old kernel 4.5.5), enable networking and use: dnf update
3. Reboot into new kernel -> doesn't boot

Actual results:
Kernel doesn't boot. Adding intel_pstate=no_hwp doesn't help either.

Expected results:
Kernel boots

Additional info:

Comment 1 ell1e 2016-07-07 13:43:52 UTC

The hardware in question is the Thinkpad Yoga 260 from Lenovo.

Comment 2 Josh Boyer 2016-07-07 13:56:46 UTC

This is most likely caused by an Intel microcode update and is a duplicate of bug 1353103.

If you add 'dis_ucode_ldr' to the kernel command line, does 4.6.3 boot?

Comment 3 ell1e 2016-07-07 15:34:36 UTC

I can confirm dis_ucode_ldr fixes it!

Comment 4 Josh Boyer 2016-07-07 15:38:45 UTC

(In reply to Jonas Thiem from comment #3)
> I can confirm dis_ucode_ldr fixes it!

Good because it confirms the cause.  But the cmdline parameter is unfortunately only a workaround.  The fix will have to come from the BIOS/UEFI vendor, or with further updated microcode.

*** This bug has been marked as a duplicate of bug 1353103 ***