19.4. Known Issues

SELinux MLS policy is not supported with kernel version 4.14

SELinux Multi-Level Security (MLS) Policy denies unknown classes and permissions, and kernel version 4.14 in the kernel-alt packages recognizes the map permission, which is not defined in any policy. Consequently, every command on a system with active MLS policy and SELinux in enforcing mode terminates with the Segmentation fault error. A lot of SELinux denial warnings occurs on systems with active MLS policy and SELinux in permissive mode. The combination of SELinux MLS policy with kernel version 4.14 is not supported.

ipmitool communicates with BMC only when IPMI_SI=no on Cavium ThunderX

When starting ipmi.service with the systemctl command, the default configuration attempts to load the ipmi_si driver. On Cavium ThunderX systems, which do not have an IPMI SI device, ipmi.service incorrectly removes the ipmi_devintf driver. Consequently, the ipmitool utility in the kernel is not able to communicate with the Baseboard Management Controller (BMC). To work around this problem, edit the /etc/sysconfig/ipmi file and set the IPMI_SI variable as follows:
IPMI_SI=no
Then reboot the operating system if necessary. As a result, the correct drivers are loaded and ipmitoo can communicate with BMC through the /dev/ipmi0/ directory. (BZ#1448181)

Putting SATA ALPM devices into low power mode does not work correctly

When using the following commands to enable and disable low power mode for Serial Advanced Technology Attachment (SATA) devices using the Aggressive Link Power Management (ALPM) power management protocol on the 64-bit ARM systems, SATA does not work correctly:
tuned-adm profile powersave
tuned-adm profile performance
Consequently, SATA failures stop all disk I/O, and users have to reboot the operating system to fix it. To work around this problem, use one of the following options:
  • Do not put the system into the powersave profile
  • Check with your hardware vendor for firmware updates that might fix the bug with ALPM
(BZ#1430391)

Setting tuned to network-latency causes system hang on ARM

If the tuned profile is set to network-latency on the 64-bit ARM systems, the operating system becomes unresponsive, and the kernel prints a backtrace to the serial console. To work around this problem, do not set the tuned profile to network-latency. (BZ#1503121)

modprobe succeeds to load kernel modules with incorrect parameters

When attempting to load a kernel module with an incorrect parameter using the modprobe command, the incorrect parameter is ignored, and the module loads as expected on Red Hat Enterprise Linux 7 for ARM and for IBM Power LE (POWER9).
Note that this is a different behavior compared to Red Hat Enterprise Linux for traditional architectures, such as AMD64 and Intel 64, IBM z Systems and IBM Power Systems. On these systems, modprobe exits with an error, and the module with an incorrect parameter does not load in the described situation.
On all architectures, an error message is recorded in the dmesg output. (BZ#1449439)