Chapter 9. Known issues

This part describes known issues in Red Hat Enterprise Linux 8.3.

9.1. Installer and image creation

The auth and authconfig Kickstart commands require the AppStream repository

The authselect-compat package is required by the auth and authconfig Kickstart commands during installation. Without this package, the installation fails if auth or authconfig are used. However, by design, the authselect-compat package is only available in the AppStream repository.

To work around this problem, verify that the BaseOS and AppStream repositories are available to the installer or use the authselect Kickstart command during installation.

(BZ#1640697)

The reboot --kexec and inst.kexec commands do not provide a predictable system state

Performing a RHEL installation with the reboot --kexec Kickstart command or the inst.kexec kernel boot parameters do not provide the same predictable system state as a full reboot. As a consequence, switching to the installed system without rebooting can produce unpredictable results.

Note that the kexec feature is deprecated and will be removed in a future release of Red Hat Enterprise Linux.

(BZ#1697896)

Network access is not enabled by default in the installation program

Several installation features require network access, for example, registration of a system using the Content Delivery Network (CDN), NTP server support, and network installation sources. However, network access is not enabled by default, and as a result, these features cannot be used until network access is enabled.

To work around this problem, add ip=dhcp to boot options to enable network access when the installation starts. Optionally, passing a Kickstart file or a repository located on the network using boot options also resolves the problem. As a result, the network-based installation features can be used.

(BZ#1757877)

The new osbuild-composer back end does not replicate the blueprint state from lorax-composer on upgrades

Image Builder users that are upgrading from the lorax-composer back end to the new osbuild-composer back end, blueprints can disappear. As a result, once the upgrade is complete, the blueprints do not display automatically. To work around this problem, perform the following steps.

Prerequisites

  • You have the composer-cli CLI utility installed.

Procedure

  1. Run the command to load the previous lorax-composer based blueprints into the new osbuild-composer back end:

    $ for blueprint in $(find /var/lib/lorax/composer/blueprints/git/workspace/master -name '*.toml'); do composer-cli blueprints push "${blueprint}"; done

As a result, the same blueprints are now available in osbuild-composer back end.

Additional resources

(BZ#1897383)

Self-signed HTTPS server cannot be used in Kickstart installation

Currently, the installer fails to install from a self-signed https server when the installation source is specified in the kickstart file and the --noverifyssl option is used:

url --url=https://SERVER/PATH --noverifyssl

To work around this problem, append the inst.noverifyssl parameter to the kernel command line when starting the kickstart installation.

For example:

inst.ks=<URL> inst.noverifyssl

(BZ#1745064)

GUI installation might fail if an attempt to unregister using the CDN is made before the repository refresh is completed

Since RHEL 8.2, when registering your system and attaching subscriptions using the Content Delivery Network (CDN), a refresh of the repository metadata is started by the GUI installation program. The refresh process is not part of the registration and subscription process, and as a consequence, the Unregister button is enabled in the Connect to Red Hat window. Depending on the network connection, the refresh process might take more than a minute to complete. If you click the Unregister button before the refresh process is completed, the GUI installation might fail as the unregister process removes the CDN repository files and the certificates required by the installation program to communicate with the CDN.

To work around this problem, complete the following steps in the GUI installation after you have clicked the Register button in the Connect to Red Hat window:

  1. From the Connect to Red Hat window, click Done to return to the Installation Summary window.
  2. From the Installation Summary window, verify that the Installation Source and Software Selection status messages in italics are not displaying any processing information.
  3. When the Installation Source and Software Selection categories are ready, click Connect to Red Hat.
  4. Click the Unregister button.

After performing these steps, you can safely unregister the system during the GUI installation.

(BZ#1821192)

Registration fails for user accounts that belong to multiple organizations

Currently, when you attempt to register a system with a user account that belongs to multiple organizations, the registration process fails with the error message You must specify an organization for new units.

To work around this problem, you can either:

  • Use a different user account that does not belong to multiple organizations.
  • Use the Activation Key authentication method available in the Connect to Red Hat feature for GUI and Kickstart installations.
  • Skip the registration step in Connect to Red Hat and use Subscription Manager to register your system post-installation.

(BZ#1822880)

RHEL installer fails to start when InfiniBand network interfaces are configured using installer boot options

When you configure InfiniBand network interfaces at an early stage of RHEL installation using installer boot options (for example, to download installer image using PXE server), the installer fails to activate the network interfaces.

This issue occurs because the RHEL NetworkManager fails to recognize the network interfaces in InfiniBand mode, and instead configures Ethernet connections for the interfaces.

As a result, connection activation fails, and if the connectivity over the InfiniBand interface is required at an early stage, RHEL installer fails to start the installation.

To workaround this issue, create a new installation media including the updated Anaconda and NetworkManager packages, using the Lorax tool.

For more information about creating a new installation media including the updated Anaconda and NetworkManager packages, using the Lorax tool, see Unable to install Red Hat Enterprise Linux 8.3.0 with InfiniBand network interfaces

(BZ#1890261)

Anaconda installation fails when NVDIMM device namespace set to devdax mode.

Anaconda installation fails with a trackback after booting with NVDIMM device namespace set to devdax mode before the GUI installation.

To workaround this problem, reconfigure the NVDIMM device to set the namespace to a different mode than the devdax mode before the installation begins. As a result, you can proceed with the installation.

(BZ#1891827)

9.2. Subscription management

syspurpose addons have no effect on the subscription-manager attach --auto output.

In Red Hat Enterprise Linux 8, four attributes of the syspurpose command-line tool have been added: role,usage, service_level_agreement and addons. Currently, only role, usage and service_level_agreement affect the output of running the subscription-manager attach --auto command. Users who attempt to set values to the addons argument will not observe any effect on the subscriptions that are auto-attached.

(BZ#1687900)

9.3. Infrastructure services

libmaxminddb-devel-debuginfo.rpm is removed when running dnf update

When performing the dnf update command, the binary mmdblookup tool is moved from the libmaxminddb-devel subpackage to the main libmaxmindb package. Consequently, the libmaxminddb-devel-debuginfo.rpm is removed, which might create a broken update path for this package. To work around this problem, remove the libmaxminddb-devel-debuginfo prior to the execution of the dnf update command.

Note: libmaxminddb-debuginfo is the new debuginfo package.

(BZ#1642001)

9.4. Security

Users can run sudo commands as locked users

In systems where sudoers permissions are defined with the ALL keyword, sudo users with permissions can run sudo commands as users whose accounts are locked. Consequently, locked and expired accounts can still be used to execute commands.

To work around this problem, enable the newly implemented runas_check_shell option together with proper settings of valid shells in /etc/shells. This prevents attackers from running commands under system accounts such as bin.

(BZ#1786990)

GnuTLS fails to resume current session with the NSS server

When resuming a TLS (Transport Layer Security) 1.3 session, the GnuTLS client waits 60 milliseconds plus an estimated round trip time for the server to send session resumption data. If the server does not send the resumption data within this time, the client creates a new session instead of resuming the current session. This incurs no serious adverse effects except for a minor performance impact on a regular session negotiation.

(BZ#1677754)

libselinux-python is available only through its module

The libselinux-python package contains only Python 2 bindings for developing SELinux applications and it is used for backward compatibility. For this reason, libselinux-python is no longer available in the default RHEL 8 repositories through the dnf install libselinux-python command.

To work around this problem, enable both the libselinux-python and python27 modules, and install the libselinux-python package and its dependencies with the following commands:

# dnf module enable libselinux-python
# dnf install libselinux-python

Alternatively, install libselinux-python using its install profile with a single command:

# dnf module install libselinux-python:2.8/common

As a result, you can install libselinux-python using the respective module.

(BZ#1666328)

udica processes UBI 8 containers only when started with --env container=podman

The Red Hat Universal Base Image 8 (UBI 8) containers set the container environment variable to the oci value instead of the podman value. This prevents the udica tool from analyzing a container JavaScript Object Notation (JSON) file.

To work around this problem, start a UBI 8 container using a podman command with the --env container=podman parameter. As a result, udica can generate an SELinux policy for a UBI 8 container only when you use the described workaround.

(BZ#1763210)

Negative effects of the default logging setup on performance

The default logging environment setup might consume 4 GB of memory or even more and adjustments of rate-limit values are complex when systemd-journald is running with rsyslog.

See the Negative effects of the RHEL default logging setup on performance and their mitigations Knowledgebase article for more information.

(JIRA:RHELPLAN-10431)

File permissions of /etc/passwd- are not aligned with the CIS RHEL 8 Benchmark 1.0.0

Because of an issue with the CIS Benchmark, the remediation of the SCAP rule that ensures permissions on the /etc/passwd- backup file configures permissions to 0644. However, the CIS Red Hat Enterprise Linux 8 Benchmark 1.0.0 requires file permissions 0600 for that file. As a consequence, the file permissions of /etc/passwd- are not aligned with the benchmark after remediation.

(BZ#1858866)

SELINUX=disabled in /etc/selinux/config does not work properly

Disabling SELinux using the SELINUX=disabled option in the /etc/selinux/config results in a process in which the kernel boots with SELinux enabled and switches to disabled mode later in the boot process. This might cause memory leaks and race conditions and consequently also kernel panics.

To work around this problem, disable SELinux by adding the selinux=0 parameter to the kernel command line as described in the Changing SELinux modes at boot time section of the Using SELinux title if your scenario really requires to completely disable SELinux.

(JIRA:RHELPLAN-34199)

ssh-keyscan cannot retrieve RSA keys of servers in FIPS mode

The SHA-1 algorithm is disabled for RSA signatures in FIPS mode, which prevents the ssh-keyscan utility from retrieving RSA keys of servers operating in that mode.

To work around this problem, use ECDSA keys instead, or retrieve the keys locally from the /etc/ssh/ssh_host_rsa_key.pub file on the server.

(BZ#1744108)

OpenSSL incorrectly handles PKCS #11 tokens that does not support raw RSA or RSA-PSS signatures

The OpenSSL library does not detect key-related capabilities of PKCS #11 tokens. Consequently, establishing a TLS connection fails when a signature is created with a token that does not support raw RSA or RSA-PSS signatures.

To work around the problem, add the following lines after the .include line at the end of the crypto_policy section in the /etc/pki/tls/openssl.cnf file:

SignatureAlgorithms = RSA+SHA256:RSA+SHA512:RSA+SHA384:ECDSA+SHA256:ECDSA+SHA512:ECDSA+SHA384
MaxProtocol = TLSv1.2

As a result, a TLS connection can be established in the described scenario.

(BZ#1685470)

OpenSSL in FIPS mode accepts only specific D-H parameters

In FIPS mode, Transport Security Layer (TLS) clients that use OpenSSL return a bad dh value error and abort TLS connections to servers that use manually generated parameters. This is because OpenSSL, when configured to work in compliance with FIPS 140-2, works only with D-H parameters compliant to NIST SP 800-56A rev3 Appendix D (groups 14, 15, 16, 17, and 18 defined in RFC 3526 and with groups defined in RFC 7919). Also, servers that use OpenSSL ignore all other parameters and instead select known parameters of similar size. To work around this problem, use only the compliant groups.

(BZ#1810911)

Removing the rpm-plugin-selinux package leads to removing all selinux-policy packages from the system

Removing the rpm-plugin-selinux package disables SELinux on the machine. It also removes all selinux-policy packages from the system. Repeated installation of the rpm-plugin-selinux package then installs the selinux-policy-minimum SELinux policy, even if the selinux-policy-targeted policy was previously present on the system. However, the repeated installation does not update the SELinux configuration file to account for the change in policy. As a consequence, SELinux is disabled even upon reinstallation of the rpm-plugin-selinux package.

To work around this problem:

  1. Enter the umount /sys/fs/selinux/ command.
  2. Manually install the missing selinux-policy-targeted package.
  3. Edit the /etc/selinux/config file so that the policy is equal to SELINUX=enforcing.
  4. Enter the command load_policy -i.

As a result, SELinux is enabled and running the same policy as before.

(BZ#1641631)

systemd service cannot execute commands from arbitrary paths

The systemd service cannot execute commands from /home/user/bin arbitrary paths because the SELinux policy package does not include any such rule. Consequently, the custom services that are executed on non-system paths fail and eventually logs the Access Vector Cache (AVC) denial audit messages when SELinux denied access. To work around this problem, do one of the following:

  • Execute the command using a shell script with the -c option. For example,

    bash -c command
  • Execute the command from a common path using /bin, /sbin, /usr/sbin, /usr/local/bin, and /usr/local/sbin common directories.

(BZ#1860443)

RHEL 8 system with the Server with GUI package group cannot be remediated using the e8 profile

Using the OpenSCAP Anaconda Add-on to harden the system on the Server With GUI package group with profiles that select rules from the Verify Integrity with RPM group requires an extreme amount of RAM on the system. This problem is caused by the OpenSCAP scanner; for more details see Scanning large numbers of files with OpenSCAP causes systems to run out of memory. As a consequence, the hardening of the system using the RHEL 8 Essential Eight (e8) profile is not successful. To work around this problem, choose a smaller package group, for example, Server, and install additional packages that you require after the installation. As a result, the system will have a smaller number of packages, the scanning will require less memory, and therefore the system can be hardened automatically.

(BZ#1816199)

rpm_verify_permissions fails in the CIS profile

The rpm_verify_permissions rule compares file permissions to package default permissions. However, the Center for Internet Security (CIS) profile, which is provided by the scap-security-guide packages, changes some file permissions to be more strict than default. As a consequence, verification of certain files using rpm_verify_permissions fails.

To work around this problem, manually verify that these files have the following permissions:

  • /etc/cron.d (0700)
  • /etc/cron.hourly (0700)
  • /etc/cron.monthly (0700)
  • /etc/crontab (0600)
  • /etc/cron.weekly (0700)
  • /etc/cron.daily (0700)

(BZ#1843913)

Kickstart uses org_fedora_oscap instead of com_redhat_oscap in RHEL 8

The Kickstart references the Open Security Content Automation Protocol (OSCAP) Anaconda add-on as org_fedora_oscap instead of com_redhat_oscap which might cause confusion. That is done to preserve backward compatibility with Red Hat Enterprise Linux 7.

(BZ#1665082)

Certain sets of interdependent rules in SSG can fail

Remediation of SCAP Security Guide (SSG) rules in a benchmark can fail due to undefined ordering of rules and their dependencies. If two or more rules need to be executed in a particular order, for example, when one rule installs a component and another rule configures the same component, they can run in the wrong order and remediation reports an error. To work around this problem, run the remediation twice, and the second run fixes the dependent rules.

(BZ#1750755)

OSCAP Anaconda Addon does not install all packages in text mode

The OSCAP Anaconda Addon plugin cannot modify the list of packages selected for installation by the system installer if the installation is running in text mode. Consequently, when a security policy profile is specified using Kickstart and the installation is running in text mode, any additional packages required by the security policy are not installed during installation.

To work around this problem, either run the installation in graphical mode or specify all packages that are required by the security policy profile in the security policy in the %packages section in your Kickstart file.

As a result, packages that are required by the security policy profile are not installed during RHEL installation without one of the described workarounds, and the installed system is not compliant with the given security policy profile.

(BZ#1674001)

OSCAP Anaconda Addon does not correctly handle customized profiles

The OSCAP Anaconda Addon plugin does not properly handle security profiles with customizations in separate files. Consequently, the customized profile is not available in the RHEL graphical installation even when you properly specify it in the corresponding Kickstart section.

To work around this problem, follow the instructions in the Creating a single SCAP data stream from an original DS and a tailoring file Knowledgebase article. As a result of this workaround, you can use a customized SCAP profile in the RHEL graphical installation.

(BZ#1691305)

OSPP-based profiles are incompatible with GUI package groups.

GNOME packages installed by the Server with GUI package group require the nfs-utils package that is not compliant with the Operating System Protection Profile (OSPP). As a consequence, selecting the Server with GUI package group during the installation of a system with OSPP or OSPP-based profiles, for example, Security Technical Implementation Guide (STIG), OpenSCAP displays a warning that the selected package group is not compatible with the security policy. If the OSPP-based profile is applied after the installation, the system is not bootable. To work around this problem, do not install the Server with GUI package group or any other groups that install GUI when using the OSPP profile and OSPP-based profiles. When you use the Server or Minimal Install package groups instead, the system installs without issues and works correctly.

(BZ#1787156)

Installation with the Server with GUI or Workstation software selections and CIS security profile is not possible

The CIS security profile is not compatible with the Server with GUI and Workstation software selections. As a consequence, a RHEL 8 installation with the Server with GUI software selection and CIS profile is not possible. An attempted installation using the CIS profile and either of these software selections will generate the error message:

package xorg-x11-server-common has been added to the list of excluded packages, but it can't be removed from the current software selection without breaking the installation.

To work around the problem, do not use the CIS security profile with the Server with GUI or Workstation software selections.

(BZ#1843932)

Remediating service-related rules during kickstart installations might fail

During a kickstart installation, the OpenSCAP utility sometimes incorrectly shows that a service enable or disable state remediation is not needed. Consequently, OpenSCAP might set the services on the installed system to a non-compliant state. As a workaround, you can scan and remediate the system after the kickstart installation. This will fix the service-related issues.

(BZ#1834716)

Certain rsyslog priority strings do not work correctly

Support for the GnuTLS priority string for imtcp that allows fine-grained control over encryption is not complete. Consequently, the following priority strings do not work properly in rsyslog:

NONE:+VERS-ALL:-VERS-TLS1.3:+MAC-ALL:+DHE-RSA:+AES-256-GCM:+SIGN-RSA-SHA384:+COMP-ALL:+GROUP-ALL

To work around this problem, use only correctly working priority strings:

NONE:+VERS-ALL:-VERS-TLS1.3:+MAC-ALL:+ECDHE-RSA:+AES-128-CBC:+SIGN-RSA-SHA1:+COMP-ALL:+GROUP-ALL

As a result, current configurations must be limited to the strings that work correctly.

(BZ#1679512)

9.5. Networking

The iptables utility now requests module loading for commands that update a chain regardless of the NLM_F_CREATE flag

Previously, when setting a chain’s policy, the iptables-nft utility generated a NEWCHAIN message but did not set the NLM_F_CREATE flag. As a consequence, the RHEL 8 kernel did not load any modules and the resulting update chain command failed if the associated kernel modules were not manually loaded. With this update, the iptables-nft utility now requests module loading for all commands that update a chain and users are able to set a chain’s policy using the iptables-nft utility without manually loading the associated modules.

(BZ#1812666)

Support for updating packet/byte counters in the kernel was changed incorrectly between RHEL 7 and RHEL 8

When referring to an ipset command with enabled counters from an iptables rule, which specifies additional constraints on matching ipset entries, the ipset counters are updated only if all the additional constraints match. This is also problematic with --packets-gt or --bytes-gt constraints.

As a result, when migrating an iptables ruleset from RHEL 7 to RHEL 8, the rules involving ipset lookups may stop working and need to be adjusted. To work around this problem, avoid using the --packets-gt or --bytes-gt options and replace them with the --packets-lt or --bytes-lt options.

(BZ#1806882)

Unloading XDP programs fails on Netronome network cards that use the nfp driver

The nfp driver for Netronome network cards contains a bug. Therefore, unloading eXpress Data Path (XDP) programs fails if you use such cards and load the XDP program using the IFLA_XDP_EXPECTED_FD feature with the XDP_FLAGS_REPLACE flag. For example, this bug affects XDP programs that are loaded using the libxdp library. Currently, there is no workaround available for the problem.

(BZ#1880268)

9.6. Kernel

Systems with a large amount of persistent memory experience delays during the boot process

Systems with a large amount of persistent memory take a long time to boot because the initialization of the memory is serialized. Consequently, if there are persistent memory file systems listed in the /etc/fstab file, the system might timeout while waiting for devices to become available. To work around this problem, configure the DefaultTimeoutStartSec option in the /etc/systemd/system.conf file to a sufficiently large value.

(BZ#1666538)

The kernel returns false positive warnings on IBM Z systems

In RHEL 8, IBM Z systems are missing a whitelist entry for the ZONE_DMA memory zone to allow user access. Consequently, the kernel returns false positive warnings such as:

...
Bad or missing usercopy whitelist? Kernel memory exposure attempt detected from SLUB object 'dma-kmalloc-192' (offset 0, size 144)!
WARNING: CPU: 0 PID: 8519 at mm/usercopy.c:83 usercopy_warn+0xac/0xd8
...

The warnings appear when accessing certain system information through the sysfs interface. For example, by running the debuginfo.sh script.

To work around this problem, add the hardened_usercopy=off parameter to the kernel command line.

As a result, no warning messages are displayed in the described scenario.

(BZ#1660290)

The rngd service busy wait causes total CPU consumption in FIPS mode

A new kernel entropy source for FIPS mode has been added for kernels starting with version 4.18.0-193.10. Consequently, when in FIPS mode, the rngd service busy waits on the poll() system call for the /dev/random device, thereby causing consumption of 100% of CPU time. To work around this problem, stop and disable rngd by running:

# systemctl stop rngd
# systemctl disable rngd

As a result, rngd no longer busy waits on poll() in the described scenario.

(BZ#1884857)

A vmcore capture fails after memory hot-plug or unplug operation

After performing the memory hot-plug or hot-unplug operation, the event comes after updating the device tree which contains memory layout information. Thereby the makedumpfile utility tries to access a non-existent physical address. The problem appears if all of the following conditions meet:

  • A little-endian variant of IBM Power System runs RHEL 8.
  • The kdump or fadump service is enabled on the system.

Consequently, the capture kernel fails to save vmcore if a kernel crash is triggered after the memory hot-plug or hot-unplug operation.

To work around this problem, restart the kdump service after hot-plug or hot-unplug:

# systemctl restart kdump.service

As a result, vmcore is successfully saved in the described scenario.

(BZ#1793389)

Using irqpoll causes vmcore generation failure

Due to an existing problem with the nvme driver on the 64-bit ARM architectures that run on the Amazon Web Services (AWS) cloud platforms, the vmcore generation fails when you provide the irqpoll kernel command line parameter to the first kernel. Consequently, no vmcore file is dumped in the /var/crash/ directory after a kernel crash. To work around this problem:

  1. Add irqpoll to the KDUMP_COMMANDLINE_REMOVE key in the /etc/sysconfig/kdump file.
  2. Restart the kdump service by running the systemctl restart kdump command.

As a result, the first kernel boots correctly and the vmcore file is expected to be captured upon the kernel crash.

Note that the kdump service can use a significant amount of crash kernel memory to dump the vmcore file. Ensure that the capture kernel has sufficient memory available for the kdump service.

(BZ#1654962)

Debug kernel fails to boot in crash capture environment in RHEL 8

Due to memory-demanding nature of the debug kernel, a problem occurs when the debug kernel is in use and a kernel panic is triggered. As a consequence, the debug kernel is not able to boot as the capture kernel, and a stack trace is generated instead. To work around this problem, increase the crash kernel memory accordingly. As a result, the debug kernel successfully boots in the crash capture environment.

(BZ#1659609)

zlib may slow down a vmcore capture in some compression functions

The kdump configuration file uses the lzo compression format (makedumpfile -l) by default. When you modify the configuration file using the zlib compression format, (makedumpfile -c) it is likely to bring a better compression factor at the expense of slowing down the vmcore capture process. As a consequence, it takes the kdump upto four times longer to capture a vmcore with zlib, as compared to lzo.

As a result, Red Hat recommends using the default lzo for cases where speed is the main driving factor. However, if the target machine is low on available space, zlib is a better option.

(BZ#1790635)

The HP NMI watchdog does not always generate a crash dump

In certain cases, the hpwdt driver for the HP NMI watchdog is not able to claim a non-maskable interrupt (NMI) generated by the HPE watchdog timer because the NMI was instead consumed by the perfmon driver.

The missing NMI is initiated by one of two conditions:

  1. The Generate NMI button on the Integrated Lights-Out (iLO) server management software. This button is triggered by a user.
  2. The hpwdt watchdog. The expiration by default sends an NMI to the server.

Both sequences typically occur when the system is unresponsive. Under normal circumstances, the NMI handler for both these situations calls the kernel panic() function and if configured, the kdump service generates a vmcore file.

Because of the missing NMI, however, kernel panic() is not called and vmcore is not collected.

In the first case (1.), if the system was unresponsive, it remains so. To work around this scenario, use the virtual Power button to reset or power cycle the server.

In the second case (2.), the missing NMI is followed 9 seconds later by a reset from the Automated System Recovery (ASR).

The HPE Gen9 Server line experiences this problem in single-digit percentages. The Gen10 at an even smaller frequency.

(BZ#1602962)

The tuned-adm profile powersave command causes the system to become unresponsive

Executing the tuned-adm profile powersave command leads to an unresponsive state of the Penguin Valkyrie 2000 2-socket systems with the older Thunderx (CN88xx) processors. Consequently, reboot the system to resume working. To work around this problem, avoid using the powersave profile if your system matches the mentioned specifications.

(BZ#1609288)

The default 7 4 1 7 printk value sometimes causes temporary system unresponsiveness

The default 7 4 1 7 printk value allows for better debugging of the kernel activity. However, when coupled with a serial console, this printk setting can cause intense I/O bursts that can lead to a RHEL system becoming temporarily unresponsive. To work around this problem, we have added a new optimize-serial-console TuneD profile, which reduces the default printk value to 4 4 1 7. Users can instrument their system as follows:

# tuned-adm profile throughput-performance optimize-serial-console

Having a lower printk value persistent across a reboot reduces the likelihood of system hangs.

Note that this setting change comes at the expense of losing the extra debugging information.

For more information about the newly added feature, see A new optimize-serial-console TuneD profile to reduce I/O to serial consoles by lowering the printk value.

(JIRA:RHELPLAN-28940)

The kernel ACPI driver reports it has no access to a PCIe ECAM memory region

The Advanced Configuration and Power Interface (ACPI) table provided by firmware does not define a memory region on the PCI bus in the Current Resource Settings (_CRS) method for the PCI bus device. Consequently, the following warning message occurs during the system boot:

[    2.817152] acpi PNP0A08:00: [Firmware Bug]: ECAM area [mem 0x30000000-0x31ffffff] not reserved in ACPI namespace
[    2.827911] acpi PNP0A08:00: ECAM at [mem 0x30000000-0x31ffffff] for [bus 00-1f]

However, the kernel is still able to access the 0x30000000-0x31ffffff memory region, and can assign that memory region to the PCI Enhanced Configuration Access Mechanism (ECAM) properly. You can verify that PCI ECAM works correctly by accessing the PCIe configuration space over the 256 byte offset with the following output:

03:00.0 Non-Volatile memory controller: Sandisk Corp WD Black 2018/PC SN720 NVMe SSD (prog-if 02 [NVM Express])
 ...
        Capabilities: [900 v1] L1 PM Substates
                L1SubCap: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- L1_PM_Substates+
                          PortCommonModeRestoreTime=255us PortTPowerOnTime=10us
                L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
                           T_CommonMode=0us LTR1.2_Threshold=0ns
                L1SubCtl2: T_PwrOn=10us

As a result, you can ignore the warning message.

For more information about the problem, see the "Firmware Bug: ECAM area mem 0x30000000-0x31ffffff not reserved in ACPI namespace" appears during system boot solution.

(BZ#1868526)

The cxgb4 driver causes crash in the kdump kernel

The kdump kernel crashes while trying to save information in the vmcore file. Consequently, the cxgb4 driver prevents the kdump kernel from saving a core for later analysis. To work around this problem, add the novmcoredd parameter to the kdump kernel command line to allow saving core files.

(BZ#1708456)

The OPEN MPI library may trigger run-time failures with default PML

In OPEN Message Passing Interface (OPEN MPI) implementation 4.0.x series, Unified Communication X (UCX) is the default point-to-point communicator (PML). The later versions of OPEN MPI 4.0.x series deprecated openib Byte Transfer Layer (BTL).

However, OPEN MPI, when run over a homogeneous cluster (same hardware and software configuration), UCX still uses openib BTL for MPI one-sided operations. As a consequence, this may trigger execution errors. To work around this problem:

  • Run the mpirun command using following parameters:
-mca btl openib -mca pml ucx -x UCX_NET_DEVICES=mlx5_ib0

where,

  • The -mca btl openib parameter disables openib BTL
  • The -mca pml ucx parameter configures OPEN MPI to use ucx PML.
  • The x UCX_NET_DEVICES= parameter restricts UCX to use the specified devices

The OPEN MPI, when run over a heterogeneous cluster (different hardware and software configuration), it uses UCX as the default PML. As a consequence, this may cause the OPEN MPI jobs to run with erratic performance, unresponsive behavior, or crash failures. To work around this problem, set the UCX priority as:

  • Run the mpirun command using following parameters:
-mca pml_ucx_priority 5

As a result, the OPEN MPI library is able to choose an alternative available transport layer over UCX.

(BZ#1866402)

9.7. File systems and storage

The /boot file system cannot be placed on LVM

You cannot place the /boot file system on an LVM logical volume. This limitation exists for the following reasons:

  • On EFI systems, the EFI System Partition conventionally serves as the /boot file system. The uEFI standard requires a specific GPT partition type and a specific file system type for this partition.
  • RHEL 8 uses the Boot Loader Specification (BLS) for system boot entries. This specification requires that the /boot file system is readable by the platform firmware. On EFI systems, the platform firmware can read only the /boot configuration defined by the uEFI standard.
  • The support for LVM logical volumes in the GRUB 2 boot loader is incomplete. Red Hat does not plan to improve the support because the number of use cases for the feature is decreasing due to standards such as uEFI and BLS.

Red Hat does not plan to support /boot on LVM. Instead, Red Hat provides tools for managing system snapshots and rollback that do not need the /boot file system to be placed on an LVM logical volume.

(BZ#1496229)

LVM no longer allows creating volume groups with mixed block sizes

LVM utilities such as vgcreate or vgextend no longer allow you to create volume groups (VGs) where the physical volumes (PVs) have different logical block sizes. LVM has adopted this change because file systems fail to mount if you extend the underlying logical volume (LV) with a PV of a different block size.

To re-enable creating VGs with mixed block sizes, set the allow_mixed_block_sizes=1 option in the lvm.conf file.

(BZ#1768536)

Limitations of LVM writecache

The writecache LVM caching method has the following limitations, which are not present in the cache method:

  • You cannot name a writecache logical volume when using pvmove commands.
  • You cannot use logical volumes with writecache in combination with thin pools or VDO.

The following limitation also applies to the cache method:

  • You cannot resize a logical volume while cache or writecache is attached to it.

(JIRA:RHELPLAN-27987, BZ#1798631, BZ#1808012)

LVM mirror devices that store a LUKS volume sometimes become unresponsive

Mirrored LVM devices with a segment type of mirror that store a LUKS volume might become unresponsive under certain conditions. The unresponsive devices reject all I/O operations.

To work around the issue, Red Hat recommends that you use LVM RAID 1 devices with a segment type of raid1 instead of mirror if you need to stack LUKS volumes on top of resilient software-defined storage.

The raid1 segment type is the default RAID configuration type and replaces mirror as the recommended solution.

To convert mirror devices to raid, see Converting a mirrored LVM device to a RAID1 device.

(BZ#1730502)

An NFS 4.0 patch can result in reduced performance under an open-heavy workload

Previously, a bug was fixed that, in some cases, could cause an NFS open operation to overlook the fact that a file had been removed or renamed on the server. However, the fix may cause slower performance with workloads that require many open operations. To work around this problem, it might help to use NFS version 4.1 or higher, which have been improved to grant delegations to clients in more cases, allowing clients to perform open operations locally, quickly, and safely.

(BZ#1748451)

9.8. Dynamic programming languages, web and database servers

getpwnam() might fail when called by a 32-bit application

When a user of NIS uses a 32-bit application that calls the getpwnam() function, the call fails if the nss_nis.i686 package is missing. To work around this problem, manually install the missing package by using the yum install nss_nis.i686 command.

(BZ#1803161)

Symbol conflicts between OpenLDAP libraries might cause crashes in httpd

When both the libldap and libldap_r libraries provided by OpenLDAP are loaded and used within a single process, symbol conflicts between these libraries might occur. Consequently, Apache httpd child processes using the PHP ldap extension might terminate unexpectedly if the mod_security or mod_auth_openidc modules are also loaded by the httpd configuration.

With this update to the Apache Portable Runtime (APR) library, you can work around the problem by setting the APR_DEEPBIND environment variable, which enables the use of the RTLD_DEEPBIND dynamic linker option when loading httpd modules. When the APR_DEEPBIND environment variable is enabled, crashes no longer occur in httpd configurations that load conflicting libraries.

(BZ#1819607)

9.9. Identity Management

Installing KRA fails if all KRA members are hidden replicas

The ipa-kra-install utility fails on a cluster where the Key Recovery Authority (KRA) is already present, if the first KRA instance is installed on a hidden replica. Consequently, you cannot add further KRA instances to the cluster.

To work around this problem, unhide the hidden replica that has the KRA role before you add new KRA instances. You can hide it again when ipa-kra-install completes successfully.

(BZ#1816784)

Using the cert-fix utility with the --agent-uid pkidbuser option breaks Certificate System

Using the cert-fix utility with the --agent-uid pkidbuser option corrupts the LDAP configuration of Certificate System. As a consequence, Certificate System might become unstable and manual steps are required to recover the system.

(BZ#1729215)

Certificates issued by PKI ACME Responder connected to PKI CA may fail OCSP validation

The default ACME certificate profile provided by PKI CA contains a sample OCSP URL that does not point to an actual OCSP service. As a consequence, if PKI ACME Responder is configured to use a PKI CA issuer, the certificates issued by the responder may fail OCSP validation.

To work around this problem, you need to set the policyset.serverCertSet.5.default.params.authInfoAccessADLocation_0 property to a blank value in the /usr/share/pki/ca/profiles/ca/acmeServerCert.cfg configuration file:

  1. In the ACME Responder configuration file, change the line policyset.serverCertSet.5.default.params.authInfoAccessADLocation_0=http://ocsp.example.com to policyset.serverCertSet.5.default.params.authInfoAccessADLocation_0=.
  2. Restart the service and regenerate the certificate.

As a result, PKI CA will generate ACME certificates with an autogenerated OCSP URL that points to an actual OCSP service.

(BZ#1868233)

FreeRADIUS silently truncates Tunnel-Passwords longer than 249 characters

If a Tunnel-Password is longer than 249 characters, the FreeRADIUS service silently truncates it. This may lead to unexpected password incompatibilities with other systems.

To work around the problem, choose a password that is 249 characters or fewer.

(BZ#1723362)

9.10. Desktop

Disabling flatpak repositories from Software Repositories is not possible

Currently, it is not possible to disable or remove flatpak repositories in the Software Repositories tool in the GNOME Software utility.

(BZ#1668760)

Drag-and-drop does not work between desktop and applications

Due to a bug in the gnome-shell-extensions package, the drag-and-drop functionality does not currently work between desktop and applications. Support for this feature will be added back in a future release.

(BZ#1717947)

Generation 2 RHEL 8 virtual machines sometimes fail to boot on Hyper-V Server 2016 hosts

When using RHEL 8 as the guest operating system on a virtual machine (VM) running on a Microsoft Hyper-V Server 2016 host, the VM in some cases fails to boot and returns to the GRUB boot menu. In addition, the following error is logged in the Hyper-V event log:

The guest operating system reported that it failed with the following error code: 0x1E

This error occurs due to a UEFI firmware bug on the Hyper-V host. To work around this problem, use Hyper-V Server 2019 as the host.

(BZ#1583445)

9.11. Graphics infrastructures

radeon fails to reset hardware correctly

The radeon kernel driver currently does not reset hardware in the kexec context correctly. Instead, radeon falls over, which causes the rest of the kdump service to fail.

To work around this problem, disable radeon in kdump by adding the following line to the /etc/kdump.conf file:

dracut_args --omit-drivers "radeon"
force_rebuild 1

Restart the machine and kdump. After starting kdump, the force_rebuild 1 line may be removed from the configuration file.

Note that in this scenario, no graphics will be available during kdump, but kdump will work successfully.

(BZ#1694705)

Multiple HDR displays on a single MST topology may not power on

On systems using NVIDIA Turing GPUs with the nouveau driver, using a DisplayPort hub (such as a laptop dock) with multiple monitors which support HDR plugged into it may result in failure to turn on. This is due to the system erroneously thinking there is not enough bandwidth on the hub to support all of the displays.

(BZ#1812577)

Unable to run graphical applications using sudo command

When trying to run graphical applications as a user with elevated privileges, the application fails to open with an error message. The failure happens because Xwayland is restricted by the Xauthority file to use regular user credentials for authentication.

To work around this problem, use the sudo -E command to run graphical applications as a root user.

(BZ#1673073)

VNC Viewer displays wrong colors with the 16-bit color depth on IBM Z

The VNC Viewer application displays wrong colors when you connect to a VNC session on an IBM Z server with the 16-bit color depth.

To work around the problem, set the 24-bit color depth on the VNC server. With the Xvnc server, replace the -depth 16 option with -depth 24 in the Xvnc configuration.

As a result, VNC clients display the correct colors but use more network bandwidth with the server.

(BZ#1886147)

Hardware acceleration is not supported on ARM

Built-in graphics drivers do not support hardware acceleration or the Vulkan API on the 64-bit ARM architecture.

To enable hardware acceleration or Vulkan on ARM, install the proprietary Nvidia driver.

(JIRA:RHELPLAN-57914)

9.12. The web console

Unprivileged users can access the Subscriptions page

If a non-administrator navigates to the Subscriptions page of the web console, the web console displays a generic error message Cockpit had an unexpected internal error.

To work around this problem, sign in to the web console with a privileged user and make sure to check the Reuse my password for privileged tasks checkbox.

(BZ#1674337)

9.13. Red Hat Enterprise Linux System Roles

oVirt input and the elasticsearch output functionalities are not supported in System Roles Logging

The oVirt input and the elasticsearch output are not supported in System Roles Logging although they are mentioned in the README file. There is no workaround available at the moment.

(BZ#1889468)

9.14. Virtualization

Displaying multiple monitors of virtual machines that use Wayland is not possible with QXL

Using the remote-viewer utility to display more than one monitor of a virtual machine (VM) that is using the Wayland display server causes the VM to become unresponsive and the Waiting for display status message to be displayed indefinitely.

To work around this problem, use virtio-gpu instead of qxl as the GPU device for VMs that use Wayland.

(BZ#1642887)

virsh iface-\* commands do not work consistently

Currently, virsh iface-* commands, such as virsh iface-start and virsh iface-destroy, frequently fail due to configuration dependencies. Therefore, it is recommended not to use virsh iface-\* commands for configuring and managing host network connections. Instead, use the NetworkManager program and its related management applications.

(BZ#1664592)

Virtual machines sometimes fail to start when using many virtio-blk disks

Adding a large number of virtio-blk devices to a virtual machine (VM) may exhaust the number of interrupt vectors available in the platform. If this occurs, the VM’s guest OS fails to boot, and displays a dracut-initqueue[392]: Warning: Could not boot error.

(BZ#1719687)

Attaching LUN devices to virtual machines using virtio-blk does not work

The q35 machine type does not support transitional virtio 1.0 devices, and RHEL 8 therefore lacks support for features that were deprecated in virtio 1.0. In particular, it is not possible on a RHEL 8 host to send SCSI commands from virtio-blk devices. As a consequence, attaching a physical disk as a LUN device to a virtual machine fails when using the virtio-blk controller.

Note that physical disks can still be passed through to the guest operating system, but they should be configured with the device='disk' option rather than device='lun'.

(BZ#1777138)

Virtual machines using Cooperlake cannot boot when TSX is disabled on the host

Virtual machines (VMs) that use the Cooperlake CPU model currently fail to boot when the TSX CPU flag is diabled on the host. Instead, the host displays the following error message:

the CPU is incompatible with host CPU: Host CPU does not provide required features: hle, rtm

To make VMs with Cooperlake usable on such host, disable the HLE, RTM, and TAA_NO flags in the VM configuration in the VM’s XML configuration:

<feature policy='disable' name='hle'/>
<feature policy='disable' name='rtm'/>
<feature policy='disable' name='taa-no'/>

(BZ#1860743)

9.15. RHEL in cloud environments

GPU problems on Azure NV6 instances

When running RHEL 8 as a guest operating system on a Microsoft Azure NV6 instance, resuming the virtual machine (VM) from hibernation sometimes causes the VM’s GPU to work incorrectly. When this occurs, the kernel logs the following message:

hv_irq_unmask() failed: 0x5

(BZ#1846838)

kdump sometimes does not start on Azure and Hyper-V

On RHEL 8 guest operating systems hosted on the Microsoft Azure or Hyper-V hypervisors, starting the kdump kernel in some cases fails when post-exec notifiers are enabled.

To work around this problem, disable crash kexec post notifiers:

# echo N > /sys/module/kernel/parameters/crash_kexec_post_notifiers

(BZ#1865745)

Setting static IP in a RHEL 8 virtual machine on a VMWare host does not work

Currently, when using RHEL 8 as a guest operating system of a virtual machine (VM) on a VMWare host, the DatasourceOVF function does not work correctly. As a consequence, if you use use the cloud-init utility to set the the VM’s network to static IP and then reboot the VM, the VM’s network will be changed to DHCP.

(BZ#1750862)

Core dumping RHEL 8 virtual machines with certain NICs to a remote machine on Azure takes longer than expected

Currently, using the kdump utility to save the core dump file of a RHEL 8 virtual machine (VM) on a Microsoft Azure hypervisor to a remote machine does not work correctly when the VM is using a NIC with enabled accelerated networking. As a consequence, the dump file is saved after approximately 200 seconds, instead of immediately. In addition, the following error message is logged on the console before the dump file is saved.

device (eth0): linklocal6: DAD failed for an EUI-64 address

(BZ#1854037)

TX/RX packet counters do not increase after virtual machines resume from hibernation

The TX/RX packet counters stop increasing when a RHEL 8 virtual machine (VM), with a CX4 VF NIC, resumes from hibernation on Microsoft Azure. To keep the counters working, restart the VM. Note that, doing so will reset the counters.

(BZ#1876527)

RHEL 8 virtual machines fail to resume from hibernation on Azure

The GUID of the virtual function (VF), vmbus device, changes when a RHEL 8 virtual machine (VM), with SR-IOV enabled, is hibernated and deallocated on Microsoft Azure . As a result, when the VM is restarted, it fails to resume and crashes. As a workaround, hard reset the VM using the Azure serial console.

(BZ#1876519)

9.16. Supportability

redhat-support-tool does not work with the FUTURE crypto policy

Because a cryptographic key used by a certificate on the Customer Portal API does not meet the requirements by the FUTURE system-wide cryptographic policy, the redhat-support-tool utility does not work with this policy level at the moment.

To work around this problem, use the DEFAULT crypto policy while connecting to the Customer Portal API.

(BZ#1802026)

9.17. Containers

UDICA is not expected to work with 1.0 stable stream

UDICA, the tool to generate SELinux policies for containers, is not expected to work with containers that are run via podman 1.0.x in the container-tools:1.0 module stream.

(JIRA:RHELPLAN-25571)

podman system connection add does not automatically set the default connection

The podman system connection add command does not automatically set the first connection to be the default connection. To set the default connection, you must manually run the command podman system connection default <connection_name>.

(BZ#1881894)