Linux : Change installation and boot video resolution on CentOS/RHEL 7

By | October 14, 2016

Among all the new bells and whistles coming with the latest major release of RedHat Enterprise Linux platform, resolution bot both the installation process and system console have changed (higher resolution than before is default).

Unfortunately, server system does not necessarily have the newest display device or iLO, iDRAC and virtual machine consoles are out of range for these high resolutions.

It is fortunately possible to lower the resolution that will fit your console or screen.

1. To lower the resolution at installation process, simply press “TAB” at the installer boot menu, you will see a line appearing at the bottom of the screen with the following :

> vmlinuz initrd=initrd.img inst.stage2=hd:LABEL=CentOS\x207\x20x86_64 quiet

All you have to do is adding a space and append “resolution=” or “vga=” with the desired value as followed :

Alternatively, you can enter the VGA color code by entering “vga=” followed by the colour code (example : vga=785). See the chart below for more informations :

Color depth 640×480 800×600 1024×768 1280×1024 1400×1050 1600×1200
8 (256) 769 771 773 775
15 (32K) 784 787 790 793
16 (65K) 785 788 791 794 834 884
24 (16M) 786 789 792 795

2. At the boot process of the system, you will need to edit the Grub2 boot loader by pressing “e” at boot at the kernel selection screen and edit the “vmlinuz” line, append at the end of the line “video=” followed by the desired resolution such as :

Then press CTRL + X to boot.

You may make this change permanent by editing the Grub configuration. Follow the instructions of the following article : Edit Grub2 settings on RHEL/CentOS 7

NOTE : The lowest resolution supported by RHEL 7 console and installer is 400 x 375.