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Bug 2178292

Summary: systemd-getty-generator acts too early and does not detect MMIO based serial ports
Product: Red Hat Enterprise Linux 9 Reporter: Carlos Santos <casantos>
Component: systemdAssignee: Michal Sekletar <msekleta>
Status: CLOSED MIGRATED QA Contact: Frantisek Sumsal <fsumsal>
Severity: high Docs Contact:
Priority: medium    
Version: 9.1CC: dtardon, mschibli, msekleta, systemd-maint-list
Target Milestone: rcKeywords: MigratedToJIRA
Target Release: ---Flags: pm-rhel: mirror+
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2023-09-21 12:32:31 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:

Description Carlos Santos 2023-03-14 18:21:33 UTC 
Description of problem:

Customer has a machine with the Synopsys DesignWare APB UART. The serial ports
are MMIO based:

[    4.587543] dw-apb-uart.6: ttyS0 at MMIO 0x4017006000 (irq = 33, base_baud = 6250000) is a 16550A
[    4.599879] dw-apb-uart.7: ttyS1 at MMIO 0x4017007000 (irq = 16, base_baud = 6250000) is a 16550A

Kernel is configured to use ttyS0 as console:

BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.14.0-162.6.1.el9_1.x86_64 root=/dev/mapper/rhel-root ro rhgb quiet crashkernel=1G-4G:192M,4G-64G:256M,64G-:512M resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap console=ttyS0,115200n8

So on system boot, a serial-getty@ttyS0 should be be started automatically by
systemd-getty-generator but it fails to do it.

Version-Release number of selected component (if applicable):

RHEL 9.1

How reproducible:

Always

Steps to Reproduce:
1. Install RHEL 9.1 on a machine whose serial ports are MMIO-based.
2. Reboot the system
3. Check if a serial-getty@ttyS0 is started

Actual results:

serial-getty@ttyS0 is not started

Expected results:

serial-getty@ttyS0 should be started

Additional info:

From the system sosreport:

$ fgrep -w -e ttyS0 -e getty sos_commands/logs/journalctl_--no-pager_--catalog_--boot
Mar 08 09:17:25 localhost kernel: Command line: BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.14.0-162.6.1.el9_1.x86_64 root=/dev/mapper/rhel-root ro rhgb quiet crashkernel=1G-4G:192M,4G-64G:256M,64G-:512M resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap console=ttyS0,115200n8
Mar 08 09:17:25 localhost kernel: Kernel command line: BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.14.0-162.6.1.el9_1.x86_64 root=/dev/mapper/rhel-root ro rhgb quiet crashkernel=1G-4G:192M,4G-64G:256M,64G-:512M resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap console=ttyS0,115200n8
Mar 08 09:17:25 localhost kernel: printk: console [ttyS0] enabled
Mar 08 09:17:25 localhost dracut-cmdline[353]: Using kernel command line parameters:    BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.14.0-162.6.1.el9_1.x86_64 root=/dev/mapper/rhel-root ro rhgb quiet crashkernel=1G-4G:192M,4G-64G:256M,64G-:512M resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap console=ttyS0,115200n8
Mar 08 09:17:27 localhost systemd[1]: Created slice Slice /system/getty.
Mar 08 09:17:28 localhost kernel: printk: console [ttyS0] disabled
Mar 08 09:17:28 localhost kernel: dw-apb-uart.6: ttyS0 at MMIO 0x4017006000 (irq = 33, base_baud = 6250000) is a 16550A
Mar 08 09:17:28 localhost kernel: printk: console [ttyS0] enabled
-- Subject: A start job for unit getty has finished successfully
-- A start job for unit getty has finished successfully.
-- Subject: A start job for unit getty.target has finished successfully
-- A start job for unit getty.target has finished successfully.

As can be seen, ttyS0 is enabled too late. Because of this, the getty service
generator (systemd-getty-generator) does not create getty. I have
seen a similar problem on RHEL 8 and filed a bug report for it:

   MMIO-based serial port does not work during the installation but works later
   https://bugzilla.redhat.com/show_bug.cgi?id=2162741

The behavior on RHEL 9 is better, since it is still possible to install the OS.

It's possible to circumvent the problem by enabling the service explicitly:

   # systemctl enable --now serial-getty
Comment 1 Carlos Santos 2023-03-15 12:29:27 UTC 
Additional information from the customer: "When I do the same with RHEL 9.0,
it works all fine and I can update the system to RHEL 9.1 with everything
working. So I assume there must be a solution."
Comment 2 David Tardon 2023-03-16 12:57:11 UTC 
(In reply to Carlos Santos from comment #1)
> Additional information from the customer: "When I do the same with RHEL 9.0,
> it works all fine and I can update the system to RHEL 9.1 with everything
> working. So I assume there must be a solution."

This looks like a race, so I assume they were just lucky.
Comment 3 Markus Schibli 2023-03-22 08:31:37 UTC 
(In reply to David Tardon from comment #2)
> (In reply to Carlos Santos from comment #1)
> > Additional information from the customer: "When I do the same with RHEL 9.0,
> > it works all fine and I can update the system to RHEL 9.1 with everything
> > working. So I assume there must be a solution."
> 
> This looks like a race, so I assume they were just lucky.
Hi, I'm the TAM for the customer. Customer asked me to stress out, that installing RHEL 9.0 from scratch with a working login prompt on the serial console, works always. So something has changed in RHEL 9.1.
Comment 6 RHEL Program Management 2023-09-21 12:27:27 UTC 
Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.
Comment 7 RHEL Program Management 2023-09-21 12:32:31 UTC 
This BZ has been automatically migrated to the issues.redhat.com Red Hat Issue Tracker. All future work related to this report will be managed there.

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