buildroot 2021.02.1: black screen after Xorg launched
 

Hello,

Using buildroot 2021.02.1 for x64 I built root file system that contain Xorg.
Right after Xorg is launched I got black screen.

According to Xorg.0.0.log (attached) there is no error.
I tried to run: xeyes and got:
Can't open display

I noticed the following lines in Xorg.0.0.log:
On the same PC I booted Knoppix 9.1. Xorg works fine.

I noticed that Knoppix contains several files in:
/usr/share/X11/xorg.conf.d

But in my file system this folder contains only the file: 10-quirks.conf

Can you please advise what can be the reason for the black screen ?

Thank you,
Zvika

The Xorg.0.log lines you quoted are rather common:Start by trying not using the unofficially deprecated xf86-video-intel (the Intel DDX's official upstream package name) display driver that hasn't had an official release in over a decade. Most of Intel's Linux driver writers have focused in the time since mainly on the default DIX display driver "modesetting" that isn't separately packaged. To try it, simply uninstall xf86-video-intel.

Your CPU was fairly young when kernel 4.19 and xorg 1.20.10 were current. You might benefit from newer kernel and/or Xorg.

Hi mrmazda, All,

The solution is:
export DISPLAY=:0
Then I managed to run xterm, xeyes (for example)

Regarding the driver, from the following list, which should I use ?
I noticed that with Knoppix (for example), kms is used, not intel.

Following is the list from buildroot menu:
Thank you,
Zvika

It's fine to build the intel DDX Xorg/X11 display driver. It depends on KMS (Kernel Mode Setting), which is provided by the i915 kernel module (driver) in all Linux distros, including LFS and Knoppix. The modesetting DIX display driver also depends on the i915 kernel module. Every competent display driver depends on a KMS module. Just because the intel DDX is available doesn't mean you should use it. If it doesn't seem to work, try the (default) alternative, the "modesetting" DIX display driver. Try reading the primer too.

Hi mrmazda,

Highly appreciate your help.

What do you mean by "DIX display driver" ?
Is it part of the drivers in the kernel source ?

Currently I have the following (I)I message in the X log:
modeset(0): No glamor support in the X Server.

I did not find this driver in the kernel source and not in the buildroot menu.
Should I download, compile and insert it before X org is lauunched ?

Thank you,
Zvika

Did you read the link you were given that explains this, and what it is?? And again, as you've been asked MANY times before, what hardware are you working on?? You provide no details (again). After fifteen years working with such hardware, building your own kernels, writing kernel modules, etc., it's hard to know why you'd need assistance on something like that.

And why are you building a two-year-old version of things on new hardware???

Read this primer.

No.Xorg's modesetting DIX display driver depends on Xorg's Glamor support, which apparently is missing from your configuration.

https://cgit.freedesktop.org/xorg/xs...rs/modesetting

Hi mrmazda,

According to the primer:

.."drivers" required for competent X operation are:
gma500 (kernel) or i915 (kernel) plus intel (DDX) or modesetting (DIX) for Intel GPUs/IGPs

In my kernel:
CONFIG_DRM_I915=y
CONFIG_DRM_GMA500=y

How should I select "intel(DDX) or modesetting (DIX)" in buildroot configuration ?
It seems glamor.c is not compiled at all.

Thank you,
Zvika

Configuring and building a kernel have nothing to do with X11/Xorg's intel (DDX) or modesetting (DIX) display drivers. These two display drivers simply depend on the i915 kernel DRM module being loaded. They can't function otherwise.

Hi mrmazda,

Sorry. I do not understand.

You wrote: "...have nothing to do with X11/Xorg's intel (DDX) or modesetting (DIX) display drivers"

Those display drivers are supplied with Xorg ? I'm working with Xorg 1.20.10 contained in buildroot 2021.02.1

Is there something wrong in my buildroot configuration ?

Best regards,
Zvika

I don't know. I'm not a LFS user. Each XDRIVER_XF86_VIDEO item in the list in the #3 post is optional. The default is not among them. Instead, it (modesetting_drv.so, as built) is a component of the X11/Xorg xserver. As built and installed, modesetting_drv.so is located with vesa_drv.so and fbdev_drv.so, instead of with *_dri.so corresponding to each XDRIVER_XF86_VIDEO item.

Again:

• You claim to be a kernel developer with *FIFTEEN YEARS* experience.
• You don't tell us what hardware you're using (brand/model)
• You are still using a two-year old version of things on ostensibly new hardware

Is there a reason you cannot provide details, or acknowledge what you're being told?? You had to be given a primer twice, and another link which explain things. What else do you need?

Hi TBOne,

The output of /proc/cpuinfo is attached + dmesg + Xorg log.
What further info is required ?

Thank you,
Zvika

As you've been asked many, MANY times, why can't you just say "I have <brand/model> computer, with these specs?" Why do you expect us to download and trawl through your log files to try to figure out what you're working with???

Simple brand/model. Like "Dell Inspirion 1610" or "Raspberry Pi 4", 8 GB of RAM and <BRAND> video. Why is that hard???

And again, you ignore being asked why you're using two year old build on this (guessing) new project. And again, you claim to have a 'team' of kernel developers and you've been doing this 15 years...why can't you read the docs you've been provided, or know what they're talking about???

Hi TBOne,

The SBC is called C875. It's a 3U SBC with Intel Xeon E-2276ME processor with integrated Intel UHD Graphics 630.

This is not a new project. It's a project we started developing ~2 years ago. This is why I prefer not to change buildroot version.

Of course I will upgrade in case I have no other option.

As always, I read the documentation and also googled this issue, with no results.

Thank you,
Zvika