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14.3. Problems After Installation

14.3.1. Trouble With the Graphical Boot Sequence

After you finish the installation and reboot your system for the first time, it is possible that the system stops responding during the graphical boot sequence, requiring a reset. In this case, the boot loader is displayed successfully, but selecting any entry and attempting to boot the system results in a halt. This usually means a problem with the graphical boot sequence; to solve this issue, you must disable graphical boot. To do this, temporarily alter the setting at boot time before changing it permanently.

Procedure 14.3. Disabling Graphical Boot Temporarily

  1. Start your computer and wait until the boot loader menu appears. If you set your boot loader timeout period to 0, hold down the Esc key to access it.
  2. When the boot loader menu appears, use your cursor keys to highlight the entry you want to boot and press the e key to edit this entry's options.
  3. In the list of options, find the kernel line - that is, the line beginning with the keyword linux. On this line, locate the rhgb option and delete it. The option might not be immediately visible; use the cursor keys to scroll up and down.
  4. Press F10 or Ctrl+X to boot your system with the edited options.
If the system started successfully, you can log in normally. Then you will need to disable the graphical boot permanently - otherwise you will have to perform the previous procedure every time the system boots. To permanently change boot options, do the following.

Procedure 14.4. Disabling Graphical Boot Permanently

  1. Log in to the root account using the su - command:
    $ su -
  2. Use the grubby tool to find the default GRUB2 kernel:
    # grubby --default-kernel
    /boot/vmlinuz-3.10.0-229.4.2.el7.ppc64
  3. Use the grubby tool to remove the rhgb boot option from the default kernel, identified in the last step, in your GRUB2 configuration. For example:
    # grubby --remove-args="rhgb" --update-kernel /boot/vmlinuz-3.10.0-229.4.2.el7.ppc64
After you finish this procedure, you can reboot your computer. Red Hat Enterprise Linux will not use the graphical boot sequence any more. If you want to enable graphical boot in the future, follow the same procedure, replacing the --remove-args="rhgb" parameter with the --args="rhgb" paramter. This will restore the rhgb boot option to the default kernel in your GRUB2 configuration.
See the Red Hat Enterprise Linux 7 System Administrator's Guide for more information about working with the GRUB2 boot loader.

14.3.2. Booting into a Graphical Environment

If you have installed the X Window System but are not seeing a graphical desktop environment once you log into your system, you can start it manually using the startx command. Note, however, that this is just a one-time fix and does not change the log in process for future log ins.
To set up your system so that you can log in at a graphical login screen, you must change the default systemd target to graphical.target. When you are finished, reboot the computer. You will presented with a graphical login prompt after the system restarts.

Procedure 14.5. Setting Graphical Login as Default

  1. Open a shell prompt. If you are in your user account, become root by typing the su - command.
  2. Change the default target to graphical.target. To do this, execute the following command:
    # systemctl set-default graphical.target
Graphical login is now enabled by default - you will be presented with a graphical login prompt after the next reboot. If you want to reverse this change and keep using the text-based login prompt, execute the following command as root:
# systemctl set-default multi-user.target
For more information about targets in systemd, see the Red Hat Enterprise Linux 7 System Administrator's Guide.

14.3.3. No Graphical User Interface Present

If you are having trouble getting X (the X Window System) to start, it is possible that it has not been installed. Some of the preset base environments you can select during the installation, such as Minimal install or Web Server, do not include a graphical interface - it has to be installed manually.
If you want X, you can install the necessary packages afterwards. See the Knowledgebase article at https://access.redhat.com/site/solutions/5238 for information on installing a graphical desktop environment.

14.3.4. X Server Crashing After User Logs In

If you are having trouble with the X server crashing when a user logs in, one or more of your file systems can be full or nearly full. To verify that this is the problem you are experiencing, execute the following command:
$ df -h
The output will help you diagnose which partition is full - in most cases, the problem will be on the /home partition. The following is a sample output of the df command:
Filesystem                                  Size  Used Avail Use% Mounted on
/dev/mapper/vg_rhel-root                     20G  6.0G   13G  32% /
devtmpfs                                    1.8G     0  1.8G   0% /dev
tmpfs                                       1.8G  2.7M  1.8G   1% /dev/shm
tmpfs                                       1.8G 1012K  1.8G   1% /run
tmpfs                                       1.8G     0  1.8G   0% /sys/fs/cgroup
tmpfs                                       1.8G  2.6M  1.8G   1% /tmp
/dev/sda1                                   976M  150M  760M  17% /boot
/dev/dm-4                                    90G   90G     0 100% /home
In the above example, you can see that the /home partition is full, which causes the crash. You can make some room on the partition by removing unneeded files. After you free up some disk space, start X using the startx command.
For additional information about df and an explanation of the options available (such as the -h option used in this example), see the df(1) man page.

14.3.5. Is Your System Displaying Signal 11 Errors?

A signal 11 error, commonly known as a segmentation fault, means that a program accessed a memory location that was not assigned to it. A signal 11 error can occur due to a bug in one of the software programs that is installed, or faulty hardware.
If you receive a fatal signal 11 error during the installation, first make sure you are using the most recent installation images, and let Anaconda verify them to make sure they are not corrupted. Bad installation media (such as an improperly burned or scratched optical disk) are a common cause of signal 11 errors. Verifying the integrity of the installation media is recommended before every installation.
For information about obtaining the most recent installation media, see Chapter 2, Downloading Red Hat Enterprise Linux. To perform a media check before the installation starts, append the rd.live.check boot option at the boot menu. See Section 22.2.2, “Verifying Boot Media” for details.
Other possible causes are beyond this document's scope. Consult your hardware manufacturer's documentation for more information.

14.3.6. Unable to IPL from Network Storage Space (*NWSSTG)

If you are experiencing difficulties when trying to IPL from Network Storage Space (*NWSSTG), in most cases the reason is a missing PReP partition. In this case, you must reinstall the system and make sure to create this partition during the partitioning phase or in the Kickstart file.

14.3.7. The GRUB2 next_entry variable can behave unexpectedly in a virtualized environment

IBM Power System users booting their virtual environment with SLOF firmware must manually unset the next_entry grub environment variable after a system reboot. The SLOF firmware does not support block writes at boot time by design thus the bootloader is unable to clear this variable at boot time.