Bug 2457277

Summary: SMC (shared memory communication) kernel module is not present in Fedora44 which has 6.19.8-300.fc44.s390x kernel
Product: [Fedora] Fedora Reporter: IBM Bug Proxy <bugproxy>
Component: kernelAssignee: Justin M. Forbes <jforbes>
Status: CLOSED CURRENTRELEASE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: 44CC: acaringi, adscvr, airlied, bugproxy, dan, hans, hpa, jforbes, kernel-maint, linville, masami256, mchehab, nickolasjcarr, ptalbert, steved, suraj.ghimire7, tstaudt
Target Milestone: ---   
Target Release: ---   
Hardware: s390x   
OS: All   
Whiteboard:
Fixed In Version: kernel-7.0.0-62.fc45 kernel-7.0.1-200.fc44 Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-05-14 07:45:03 UTC Type: ---
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: 467765    

Description IBM Bug Proxy 2026-04-10 11:10:33 UTC

Comment 1 IBM Bug Proxy 2026-04-10 11:10:47 UTC
== Comment: #0 - Mahanta Jambigi <Mahanta.Jambigi> - 2026-04-10 05:51:53 ==
---Problem Description---
DIBS & SMC module are not part of default kernel config in Fedora44
 
---Debugger---
A debugger is not configured
 
---uname output---
Linux t83lp72.lnxne.boe 6.19.8-300.fc44.s390x #1 SMP Fri Mar 13 21:00:49 UTC 2026 s390x GNU/Linux
 
Contact Information = Mahanta.Jambigi 
 
Machine Type = LPAR 
 
---Steps to Reproduce---
 Install Fedora44 & run smc_pnet command. We will get below error. However the same command works fine on Fedora43 & internally this command load smc.ko.

[root@server ~]$ smc_pnet
smc_pnet: SMC module not loaded
[root@server ~]$

The reason for this is that CONFIG_DIBS is not set in default config. This has to be set which in-turn will set CONFIG_SMC & CONFIG_SMC_DIAG modules. This way smc.ko gets loaded when we run 'smc_pnet' command or we can load it manually using 'modprobe smc' also. Check below output from Fedora43.

[root@server ~]$ cat /boot/config-6.17.1-300.fc43.s390x | grep -i smc
CONFIG_SMC=m
CONFIG_SMC_DIAG=m
# CONFIG_SMC_LO is not set
[root@server ~]$
 
*Additional Instructions for Mahanta.Jambigi: 
-Post a private note with access information to the machine that the bug is occuring on.

== Comment: #1 - Thomas Staudt <tstaudt.com> - 2026-04-10 05:58:10 ==
This worked with Fedora 43.

Comment 2 Dan Horák 2026-04-10 11:38:17 UTC
If I see right, then https://gitlab.com/cki-project/kernel-ark/-/blob/os-build/redhat/configs/common/generic/CONFIG_DIBS being "# CONFIG_DIBS is not set" is the culprit, the SMC configs are set correctly

Comment 3 Dan Horák 2026-04-10 15:52:23 UTC
will be fixed with https://gitlab.com/cki-project/kernel-ark/-/commit/75b73b21389cbdc98fdf6a219b42795d727c7a19 in a next kernel build

Comment 4 IBM Bug Proxy 2026-05-14 07:30:27 UTC
------- Comment From Mahanta.Jambigi 2026-05-14 03:22 EDT-------
What is the latest update on this, do you have the next kernel build where SMC module is enabled?

Comment 5 Dan Horák 2026-05-14 07:45:03 UTC
The SMC module was re-enabled in kernel-7.0.0-62.fc45 and backported to F-44 as well (since kernel-7.0.1-200.fc44).