LinuxQuestions.org - [SOLVED] Cannot change screen resolution on unknown display in Centos7

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Cannot change screen resolution on unknown display in Centos7

I am running a fresh version of CentOS Linux release 7.2.1511 on an HP 640 G2 laptop and the screen resolution settings are defaulting to "Unknown Display" at 1024x768 (4:3). I know that the screen is actually 1920x1080.

When I run xrandr to try and change the modes available, i receive:

Code:

$xrandr

xrandr: Failed to get size of gamma for output default

Screen 0: minimum 1024 x 768, current 1024 x 768, maximum 1024 x 768

default connected primary 1024x768+0+0 0mm x 0mm

  1024x768      76.00*

I found a similar problem at http://www.linuxquestions.org/questi...lution-938378/
which implies that I may be using a default vesa driver.
Running cvt gives the result:

Code:

$ cvt 1920 1080 60

# 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz

Modeline "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync

At this point I am unsure if the driver is the problem or what to do about it.

Take a look into /var/log/Xorg.0.log (or _whereever_ that is now with systemd...). In there you can see with the (W) or (E) where the xorg system found warnings or errors. I guess your graphics hardware isn't detected properly or a driver is missing.

Quote:

Originally Posted by Upuetz (Post 5570172)

Thanks for letting me know to look for WW and EE, otherwise it's a hard file to navigate! There were a couple of errors and warnings, but it is focussed around one area. It looks like you may be right that a driver is missing, after looking at the following snippet of /var/log/Xorg.0.log

Code:

[    16.254] (II) VESA: driver for VESA chipsets: vesa

[    16.254] (++) using VT number 1



[    16.262] (EE) open /dev/dri/card0: No such file or directory

[    16.262] (WW) Falling back to old probe method for modesetting

[    16.262] (EE) open /dev/dri/card0: No such file or directory

[    16.262] (II) Loading sub module "fbdevhw"

[    16.262] (II) LoadModule: "fbdevhw"

[    16.263] (II) Loading /usr/lib64/xorg/modules/libfbdevhw.so

[    16.263] (II) Module fbdevhw: vendor="X.Org Foundation"

[    16.263]    compiled for 1.17.2, module version = 0.0.2

[    16.263]    ABI class: X.Org Video Driver, version 19.0

[    16.263] (**) FBDEV(1): claimed PCI slot 0@0:2:0

[    16.263] (II) FBDEV(1): using default device

[    16.263] (WW) Falling back to old probe method for vesa

[    16.263] (EE) Screen 0 deleted because of no matching config section.

How can I find the right driver?

What graphics card do you have? How can we tell what driver to use if you do not let us know what card you have. I expected you to put the entire log into a pastebin site using pastebinit utility (or similar).

Quote:

Originally Posted by Emerson (Post 5570237)

Ah okay, my bad. This ought to be right. http://paste.fedoraproject.org/387854/14676427/

I am pretty sure it is internal Intel Graphics HD 520.

Cheers,

OK, the graphics driver comes in two parts. One is in kernel and is loaded at boot time.

Code:

[ 16.262] (EE) open /dev/dri/card0: No such file or directory

^^ This tells me the kernel driver is not loaded, possibly because your kernel is too old for your Intel graphics.

The second part of the driver is loaded when Xorg loads.

Code:

[    16.253] (II) intel: Driver for Intel(R) Integrated Graphics Chipsets:

        i810, i810-dc100, i810e, i815, i830M, 845G, 854, 852GM/855GM, 865G,

        915G, E7221 (i915), 915GM, 945G, 945GM, 945GME, Pineview GM,

        Pineview G, 965G, G35, 965Q, 946GZ, 965GM, 965GME/GLE, G33, Q35, Q33,

        GM45, 4 Series, G45/G43, Q45/Q43, G41, B43

[    16.254] (II) intel: Driver for Intel(R) HD Graphics: 2000-6000

[    16.254] (II) intel: Driver for Intel(R) Iris(TM) Graphics: 5100, 6100

[    16.254] (II) intel: Driver for Intel(R) Iris(TM) Pro Graphics: 5200, 6200, P6300

^^ This implies the Xorg driver is too old, too. Your 520 is not listed.

In the end I decided not to install the driver but installed a new kernel from elrepo:

Code:

$ rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org

$ rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm

$ yum install yum-plugin-fastestmirror

$ yum --enablerepo=elrepo-kernel install kernel-ml

Everything seems to be working properly now. Thanks!