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  1. Summarizing the problem

Can't identify a needed display module which is loaded within the initramfs on boot time.

  1. Providing details and any research

After fixing the problem on the surface using Ingos's answer from here (https://raspberrypi.stackexchange.com/a/112429/118556) I know need a process to identify and "restrict" the correct module on boot time.

My Raspberry is a Pi 4 Modell B; 4 GB, ARM-Cortex-A72 4 x, 1,50 GHz, 4 GB RAM, WLAN-ac, Bluetooth 5, LAN, 4 x USB, 2 x Micro-HDMI with a Raspian Buster. Installed is LVM, Pi-hole Wireguard. The display is a Bruphny 4.0 (https://www.amazon.de/gp/product/B07XPM2ZS3).

  1. Describing what I’ve tried

Tried to understand how and where Ingo has learned such a deep understanding from Linux OS.

2

There's three ways modules get loaded

  1. With a device tree (for something like a RTC module)

  2. When the kernel detects a new USB device being connected.

  3. A list of modules to can be specified in: /etc/modules or /etc/modules-load.d/modules.conf which is just a pointer to /etc/modules

The parameters for modules and modules to blacklist are in /etc/modprobe.d

For example

# r8188eu is staging, 8188eu is off-kernel
#blacklist brcmfmac
blacklist r8188eu
options 8188eu rtw_power_mgnt=0 rtw_enusbss=0 rtw_drv_log_level=0

Or in /etc/modprobe.d/ipv6.conf

# Don't load ipv6 by default
alias net-pf-10 off
alias ipv6 off

Get that stuff correct before building your initramfs and the default settings should include the modules you need (which are usually the ones for root filesystems and network devices that are built as modules rather than built-in to the kernel).

Drivers for displays usually don't need to be built in to an initramfs as they can be loaded from the rootfs as soon as it is mounted.

  • Thank you Dougie for your answer. I have a few questions to it. Where and how can I may get such information regarding how the boot process of Linux (CentOS, Debian based) works in what serial way? What is fypov the best practice to identify the module which wasn't loaded with MODULES=list but with MODULES=most? Or any other way to identify the Bruphny display? Thanks in advance! – Lawful May 17 '20 at 16:08
  • I've never tweaked MODULES= or anything in /etc/mkinitramfs/conf.d so mine builds with MODULES=most. The only system I've got with an initramfs is an old RPiB+ which has a rootfs on a USB harddrive. Dr. Google can't find any details of your display and what modules are needed to run it for me. You may be able to ID the board by looking at the markings on driver chips. – Dougie May 17 '20 at 18:35

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