Ubuntu Linux is a great server and desktop distribution for x86 computers, but did you know that it’s also ideal for handheld and mobile embedded devices?
Ubuntu’s latest release, Gutsy Gibbon, now includes support for the embedded and mobile spaces with the Ubuntu Mobile and Embedded (UME) project. Get to know the UME project, and find out how to get started. The primary objective of this tutorial is to get you quickly acquainted with the Ubuntu embedded framework and tools. Along the way, you learn about several tools and new approaches to Linux kernel configuration and environment construction. You also learn about some other projects with goals similar to the UME project.
- Introduction to the Ubuntu Mobile and Embedded (UME) project, its architecture, and its use
- How to install and test the Hildon desktop
- How to build a development environment for a mobile device
- Other mobile platforms
=> Explore Ubuntu Mobile and Embedded [ free registration required ]
Generally service such as ssh, screen, expect, telnet etc use pty (pseudo-terminals) in master â€“ slave mode for login and other purposes. If pty setting is too low many users will not able to login to system using ssh or other commands. In this tip I will explain how to increase the maximum number of pseudo-terminals.
pty man page defines pseudo-terminal as follows:
A pseudo-terminal is a pair of virtual character devices that provide a bidirectional communication channel. One end of the channel is called the master; the other end is called the slave. The slave end of the pseudo-terminal provides an interface that behaves exactly like a classical terminal. A process that expects to be connected to a terminal, can open the slave end of a pseudo-terminal and then be driven by a program that has opened the master end. Anything that is written on the master end is provided to the process on the slave end as though it was input typed on a terminal.
List the maximum number of Pseudo-terminals
Just run the following command to list / display the maximum number of Pseudo-terminals under Linux
$ cat /proc/sys/kernel/pty/max
Increase the maximum number of Pseudo-terminals (PTY)
If you have large Linux installation such as University or ISP login service you need to increase the PTYs to allow more login sessions. Open kernel configuration file – /etc/sysctl.conf:
# vi /etc/sysctl.conf
Append following config directive (support 5120 ptys)
kernel.pty.max = 5120
Save and close the file. Reload the changes:
# sysctl -p
Verify that the new maximum number of pseudo-terminals value is changed, enter:
$ cat /proc/sys/kernel/pty/max
=> Refer to sysctl, proc, and pty man pages for more information.
A device driver is computer program allowing other computer programs to interact with a computer hardware device. Writing a Linux device driver is considered as a black art by many. If you ever been tempted to try writing a device driver, this howto will serve as a kick start guide:
For many seasoned Linux developers, device drivers still remain a bit of a mysterious black art practiced by a select few. While no single article could possibly attempt to covered everything there is to know about writing drivers, Valerie Henson gives us a brief taste of what’s involved, by implementing a device to return “Hello World” using all the major driver frameworks.
On a related note if you just want get a comprehensive overview of kernel configuration and building, a critical task for Linux users and administrators, try Linux Kernel in a Nutshell
/dev/hello_world: A Simple Introduction to Device Drivers under Linux (linuxdevcenter.com)
Compiling a custom kernel has its advantages and disadvantages. However, new Linux user/admin find it difficult to compile Linux kernel. Compiling kernel needs to understand few things and then type a couple of commands. This step by step howto covers compiling Linux kernel version 4.20 under an Ubuntu or Debian Linux. The following instructions successfully tested on an RHEL 7/CentOS 7 (and clones), Debian Linux, Ubuntu Linux and Fedora Linux 28. However, instructions remain the same for any other Linux distribution.