Chapter 60. Kernel

kexec fails when secondary cores do not offline

Under certain circumstances, secondary-core offlining fails on AppliedMicro X-Gene platforms like HP ProLiant m400 and AppliedMicro Mustang. As a consequence, the kernel sometimes fails to trigger the kdump crash dump mechanism through kexec when a kernel panic occurs. As a result, the kernel crash dump file is not saved. (BZ#1218374)

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#1380447)

Wacom Cintiq 12WX is not redetected when unplugged and plugged in quickly

When unplugging and quickly plugging in Wacom Cintiq 12WX within the same USB port, the tablet is currently not recognized. To work around this problem, wait 3-5 seconds before plugging the tablet back in. (BZ#1458354)

Installing to some IBM POWER8 machines using a Virtual DVD fails when starting GUI

Red Hat Enterprise Linux 7.4 can fail to install on some IBM POWER8 hardware (including S822LC machines) while starting the Anaconda GUI.
The problem is characterized by errors starting X11, followed by a Pane is dead message in the Anaconda screen.
The workaround is to append inst.text to the kernel command line and install in text mode.
This issue is confined to Virtual DVD installations, additional testing with the netboot image allows GUI installation. (BZ#1377857)

Entering full screen mode using a keyboard shortcut causes display problems on VMWare ESXi 5.5

When using Red Hat Enterprise Linux 7.4 as a virtual machine guest running on a VMWare ESXi 5.5 host, pressing Ctrl+Alt+Enter to enter full screen mode in the console causes the display to become unusable. At the same time, errors such as the following example are saved into the system log (dmesg):
[drm:vmw_cmdbuf_work_func [vmwgfx]] *ERROR* Command buffer error.
To work around this problem, shut down the virtual machine, open its .vmx configuration file, and add or modify the following parameters:
svga.maxWidth = X
svga.maxHeight = Y
svga.vramSize = "X * Y * 4"
In the above, replace X and Y with the horizontal and vertical resolution of your screen. The svga.vramSize parameter takes a value that is equal to X times Y times 4. An example setup for a screen with a resolution of 1920x1080 therefore is:
svga.maxWidth = 1920
svga.maxHeight = 1080
svga.vramSize = "8294400"
Note that VMWare ESXi 5.5 is the only version reported to encounter this bug; other versions can enter full screen mode without problems. (BZ#1451242)

KSC currently does not support xz compression

The Kernel module Source Checker (the ksc tool) is currently unable to process the xz compression method and reports the following error:
Invalid architecture, supported architectures are x86_64, ppc64, s390x
Until this limitation is resolved, system administrators should manually uncompress any third party modules using xz compression, before running the ksc tool. (BZ#1463600)