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Bug 1603017

Summary: [Hyper-V][RHEL7.6]Hyper-V console goes into blank/hang state after server crash until reboot due to no hyperv_fb in kdump initramfs
Product: Red Hat Enterprise Linux 7 Reporter: HuijingHei <hhei>
Component: kexec-toolsAssignee: Kairui Song <kasong>
Status: CLOSED ERRATA QA Contact: HuijingHei <hhei>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.6CC: boyang, hhei, kasong, ldu, leiwang, piliu, v-chvale, vkuznets, xiaofwan, xiawu, xuli, yacao
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: kexec-tools-2.0.15-20 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1637753 (view as bug list) Environment:
Last Closed: 2018-10-30 11:29:39 UTC Type: Bug
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: 1637753    

Description HuijingHei 2018-07-19 02:15:04 UTC
Description of problem:
Due to non-availability of Hyper-V video driver hyperv_fb in kdump
initramfs, the console seems to be in hang state with no text over it.

Version-Release number of selected component (if applicable):
kexec-tools-2.0.15-16.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Start os
2. Add "crashkernel=auto" to kernel parameter and reboot
3. Start kdump service and check kdump is running
# kdumpctl status
Kdump is operational
4. Check the kdump initramfs does not include hyperv_fb
# lsinitrd /boot/initramfs-3.10.0-915.el7.x86_64kdump.img | grep hyperv_fb
5. Trigger the crash and check the console
# echo c > /proc/sysrq-trigger

Actual results:
After kernel crash, the console seems to be in hang state with no text
over it until reboot

Expected results:
The logs will be visible over console after crash

Additional info:
If add hyperv_fb in kdump initramfs, the logs will be visible over console
1) Ensure /etc/kdump.conf contains the following line :
extra_modules hyperv_fb
2) Restart kdump service and check the kdump initramfs including the
hyperv_fb module
# lsinitrd /boot/initramfs-3.10.0-915.el7.x86_64kdump.img | grep hyperv_fb
Arguments: --hostonly --hostonly-cmdline --hostonly-i18n -o 'plymouth
dash resume ifcfg' --mount '/dev/mapper/rhel_bootp--73--131--181-root
/sysroot xfs defaults' --add-drivers ' hyperv_fb'
--no-hostonly-default-device -f
-rw-r--r--   1 root     root         6636 Jun 22 20:09
usr/lib/modules/3.10.0-915.el7.x86_64/kernel/drivers/video/hyperv_fb.ko.xz
3) Trigger the crash and check the console, check logs will be visible
over console
# echo c > /proc/sysrq-trigger

Refer to https://access.redhat.com/solutions/3500231 and
https://bugzilla.redhat.com/show_bug.cgi?id=1228774

Comment 5 HuijingHei 2018-09-12 06:36:05 UTC
Verify passed with kexec-tools-2.0.15-21.el7.x86_64.

@Emma, thanks for your reminder.

Comment 8 errata-xmlrpc 2018-10-30 11:29:39 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:3240