Fixing USB Problems Ubuntu Server on Raspberry 4

When trying to rung Ubunto Server on a Raspberry 4 with 4 GB RAM, you might end up with the same problem as me: USB is not working at all.

The cause is a kernel bug affecting 4 GB version of the Raspberry 4 Model B only. 1 and 2 GB versions are working quite fine.

The issue has been identified and it’s been found to be a kernel bug with a solution in the works that being tested. In the meantime, you can access to your Raspberry Pi 4 4GB USB ports by limiting the memory to 3GB in /boot/firmware/usercfg.txt […]

To limit the available RAM to 3 GB just add


to the usercfg.txt.


hacks raspberry

Raspberry Pi – Setting a static IPv4 address

It run me mad, as I tried to change the IP address of my Raspberry to a static one. I changed literally everything in  /etc/network/interfaces and reloaded, restarted and reboot the device over and over.

iface eth0 inet static
gateway 192.168.0.

As the above configuration did not help a lot, I figured out that based on the Raspberry model, you need to change settings on various places.

First run

cat /proc/cpuinfo

to determine you model. While getting something like

pi@raspberrypi:~ $ cat /proc/cpuinfo
processor    : 0
model name    : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS    : 2.00
Features    : half thumb fastmult vfp edsp java tls
CPU implementer    : 0x41
CPU architecture: 7
CPU variant    : 0x0
CPU part    : 0xb76
CPU revision    : 7

Hardware    : BCM2708
Revision    : 0004
Serial        : 000000004715b608

you need to use the hardware revision and

Model and Pi Revision 256MB Hardware Revision Code from cpuinfo
Model B Revision 1.0 256MB 0002
Model B Revision 1.0 + ECN0001 (no fuses, D14 removed) 256MB 0003
Model B Revision 2.0
Mounting holes
256MB 0004
Model A
Mounting holes
256MB 0007
Model B Revision 2.0
Mounting holes
512MB 000d
Model B+ 512MB 0010
Compute Module 512MB 0011
Model A+ 256MB 0012
Pi 2 Model B 1GB a01041 (Sony, UK)
a21041 (Embest, China)
PiZero 512MB 900092

Based on this information you need

Model a

Static IP addresses in /etc/network/interfaces is not the “prefered” way,as it is an old way and DHCPCD5 is installed.

Model b

Static IP addresses are configured in the /etc/dhcpcd.conf and it is  required that /etc/network/interfaces is set to manually.

iface eth0 inet manual

That’s all…


Locating unknown Raspberry Pi device in your Network

Just as a quick hint, once you have set up a new Raspberry Pi device (or probably any other device) which you don’t know, simply run the arp command to find out about your neighborhood.


arp -a

will make usage of the ARP protocol and give you some interesting information about some devices in your network.

arp -a

In my very case, I was told, the newly installed Raspberry Pi got the IPv4 address