Chapter 21. Kernel

Certain NIC firmware can become unresponsive with the bnx2x driver

Due to a bug in the unload sequence of the pre-boot drivers, the firmware of some internet adapters can become unresponsive after the bnx2x driver takes over the device. The bnx2x driver detects the problem and returns the message in the kernel log:
Storm stats were not updated for 3 times.
To work around this problem, apply the latest NIC firmware updates provided by your hardware vendor. As a result, unloading of the pre-boot firmware now works as expected and the firmware no longer hangs after bnx2x takes over the device. (BZ#1012684)

e1000e cards might not get an IPv4 address

Some e1000e network interface cards (NICs) might fail to get an IPv4 address assigned after the system is rebooted. To work around this problem, add the following line to the /etc/sysconfig/network-scripts/ifcfg-<interface> file:
LINKDELAY=10
(BZ#822725)

The ecb kernel module fails when dracut is not upgraded

When upgrading only the kernel rpm from Red Hat Enterprise Linux 6.7 to version 6.8, upgrade the dracut package to the latest version (dracut-004-409.el6.rpm).
Upgrading dracut enables the ecb module to work. The ecb kernel module is needed by the drbg kernel module when using the Advanced Encryption Standard (AES) implementation on non-x86 architectures. If you do not upgrade dracut, the drbg AES implementation fails with a warning message, although other drbg modules still work. (BZ#1315832)

Guests sometimes fail to boot on ESXi 5.5

When running Red Hat Enterprise Linux 7 guests on a VMware ESXi 5.5 hypervisor, certain components currently initialize with incorrect memory type range register (MTRR) values or incorrectly reconfigure MTRR values across boots. This sometimes causes the guest kernel to panic or the guest to become unresponsive during boot.
To work around this problem, add the `disable_mtrr_trim` option to the guest's kernel command line, which enables the guest to continue booting when MTRRs are configured incorrectly. Note that with this option, the guest prints `WARNING: BIOS bug` messages during boot, which you can safely ignore. (BZ#1422774)

File-system corruption due to incorrect flushing of cache has been fixed but I/O operations can be slower

Due to a bug in the megaraid_sas driver, file-system corruption previously occurred in some cases when the file system was used with a disk-write back cache during system shutdown, reboot, or power loss. This update fixes megaraid_sas to transfer the flush cache commands correctly to the raid card. As a result, if you also update the raid card firmware, the file-system corruption no longer occurs under the described circumstances.
With Broadcom megaraid_sas raid adapter, you can check the functionality in the system log (dmesg). The proper functionality is indicated by the following text string:
FW supports sync cache Yes
Note that this fix can slow down I/O operations because the cache is now flushed properly. (BZ#1392499)