Troubleshooting

Manjaro is freezing at startup

If Manjaro is freezing on the splash screen when booting up, try to boot without splash.

I have problems with my virtual machine

• Don't work on the live image, install it first then get to work.

My interrupt is registered, but it does not trigger.

Try changing the GPIO used for the interrupt.

The compilation fails

• Check the path to your compiler.
• Check if the following programs are installed: bison, flex, libssl-dev.
• Check that arm-none-linux-gnueabihf-gcc is still in your path. Remember that the export command is forgotten when you close or change terminal.

Compilation tells me about implicit declaration

You did not include some libraries.

• <linux/module.h> always
• <linux/uaccess.h> for copy_from_user and copy_to_user
• <linux/fs.h> for file_operations
• <linux/cdev.h> for character device handling

I'm pretty sure my LKM is fine, but I can't insert it into the kernel

• Try rebooting the board.
• Check that you compiled it for the correct kernel version. $ uname -r and $ modinfo myLKM.ko should return the same kernel version.

Putting my process to sleep with wait_interruptible() crashes my kernel

• Check that the process is not holding a lock when put to sleep. You can't do that and the kernel thus crashes.

My BBB seems to not boot on the Linux I flashed on my SD card

The BBB has internal memory on which you might already have another Linux installed. You can force your board to boot on the SD card by pressing the S2 button and resetting the board while keeping the button pressed.

When using cat to read my eeprom device, the output never stops

cat is issuing read() calls to your device until it reads an end-of-file (EOF). This happens when the read() function returns 0. While we return a value larger than zero, cat keeps on calling read(), hence the infinite output.

Instead of using cat, use head: $ head -n 1 /dev/mydevice.

My virtual machine cannot ssh to the BBB

If scanning with nmap does not return any result on the 192.168.7.0/24 sub-network, make sure that you did not select the BeagleBoneBlack in your Virtualbox settings, under Devices > USB. This would make the interface unavailable from your host, hence removing the network interface that the guest is not able to manage correctly.

If that does not work, try to add the network interface in the Virtualbox settings.

1. Shut down your VM
2. Go to the settings of your VM
3. Go to Network
4. Go to the Adapter 2 tab
5. Enable it with the following settings:

• Attached to: Bridged Adapter
• Name: <-- select the name of the USB network interface created by the BBB

ip a might still not see the proper interface, but you should be able to establish an SSH connection on the address 192.168.7.2.

When compiling the kernel, I get error junk at end of line first unrecognized character is #

In the folder containing the Linux 4.19 kernel source, open the file arch/arm/mm/proc-v7.S. On line 640, change the line .section ".proc.info.init", #alloc to .section ".proc.info.init", "a".

The kernel version on my BBB is not correct

If you see another version than expected (such as 3.8) on the BBB, you are probably booting from the emmc rather than the SD card. To make sure you are booting from the SD card, remove the power supply (USB cable), press and hold the button next to the SD card slot, plug the power supply in. When the blue LEDs start flashing, release the button. Guide here

Kernel compilation tells me openssl/bio.h not found

Install the package libssl-dev.

I forgot the password of my virtual machine account 🙃

• Restart you VM and hold shift in order to display the GRUB menu. It should show you a list of OS names with an asterisk in front of the default option.
• Using the arrow keys, highlight the default option and press e. It should open an editor.
• Locate the line starting with linux. On that line, replace ro by rw and add init=/bin/bash (on the same line).
• Press F10 to restart the VM and you should start on a root prompt, i.e. starting with #.
• Change your password using passwd <username> (e.g. passwd dlh).
• Restart the VM again and voilà.