Book Image

Mastering Embedded Linux Programming

By : Chris Simmonds
Book Image

Mastering Embedded Linux Programming

By: Chris Simmonds

Overview of this book

Mastering Embedded Linux Programming takes you through the product cycle and gives you an in-depth description of the components and options that are available at each stage. You will begin by learning about toolchains, bootloaders, the Linux kernel, and how to configure a root filesystem to create a basic working device. You will then learn how to use the two most commonly used build systems, Buildroot and Yocto, to speed up and simplify the development process. Building on this solid base, the next section considers how to make best use of raw NAND/NOR flash memory and managed flash eMMC chips, including mechanisms for increasing the lifetime of the devices and to perform reliable in-field updates. Next, you need to consider what techniques are best suited to writing applications for your device. We will then see how functions are split between processes and the usage of POSIX threads, which have a big impact on the responsiveness and performance of the final device The closing sections look at the techniques available to developers for profiling and tracing applications and kernel code using perf and ftrace.
Table of Contents (16 chapters)
15
Index

Threads

Now it is time to look at multi-threaded processes. The programming interface for threads is the POSIX threads API, which was first defined in IEEE POSIX 1003.1c standard (1995), commonly known as Pthreads. It was implemented as an additional part of the C library, libpthread.so. There have been two versions of Pthreads over the last 15 years or so, Linux Threads and the Native POSIX Thread Library (NPTL). The latter is much more compliant with the specification, particularly with regard to the handling of signals and process IDs. It is pretty dominant now, but you may come across some older versions of uClibc that use Linux Threads.

Creating a new thread

The function to create a thread is pthread_create(3):

int pthread_create(pthread_t *thread, const pthread_attr_t *attr, void *(*start_routine) (void *), void *arg);

It creates a new thread of execution which begins at the function start_routine and places a descriptor in pthread_t pointed to by thread. It inherits the scheduling parameters...