Chapter 25. Kernel

The following RAID controller cards are no longer supported. However, the aacraid driver still detects them. Thus, they are marked as not supported in the dmesg output.

The following cards detected by aacraid are also no longer supported but they are not identified as not supported in the dmesg output:

When the hpsa_allow_any option is used, the hpsa driver allows the use of PCI IDs that are not listed in the driver's pci-id table. Thus, cards detected when this option is used, are not supported in Red Hat Enterprise Linux 7.

The following cciss controllers are no longer supported:

The systemd service does not spawn the getty tool on the /dev/hvc0/ virtio console if the virtio console driver is not found before loading kernel modules at system startup. As a consequence, a TTY terminal does not start automatically after the system boot when the system is running as a KVM guest. To work around this problem, start getty on /dev/hvc0/ after the system boot. The ISA serial device, which is used more commonly, works as expected.

A previously applied patch is causing a memory leak when creating symbolic links over NFS. Consequently, if creating a very large number of symbolic links, on a scale of hundreds of thousands, the system may report the out of memory status.

The Linux kernel Non-Uniform Memory Access (NUMA) balancing does not always work correctly in Red Hat Enterprise Linux 7. As a consequence, when the numa_balancing parameter is set, some of the memory can move to an arbitrary non-destination node before moving to the constrained nodes, and the memory on the destination node also decreases under certain circumstances. There is currently no known workaround available.

The QLogic 1G iSCSI Adapter present in the system can cause a call trace error when the qla4xx driver is sharing the interrupt line with the USB sub-system. This error has no impact on the system functionality. The error can be found in the kernel log messages located in the /var/log/messages file. To prevent the call trace from logging into the kernel log messages, add the nousb kernel parameter when the system is booting.

In the Kernel Dump Configuration window, selecting the Raw device option in the Target settings tab does not work. To work around this problem, edit the kdump.conf file manually.

An attempt to remove the bnx2x module while the bnx2fc driver is processing a corrupted frame causes a kernel panic. To work around this problem, shut down any active FCoE interfaces before executing the modprobe -r bnx2x command.

Due to a wrong buffer size calculation in the makedumpfile utility, an OOM error could occur with a high probability. As a consequence, the vmcore file cannot be captured under certain circumstances. No workaround is currently available.