|
Embedded Linux Primer: A Practical, Real-World ApproachWorse yet, a page fault handler has not yet been installed at this early stage, so all you get is an unexplained system crash. At this early stage in the boot cycle, you are pretty much guaranteed not to have any error messages to help you figure out what's wrong. You are wise to consider delaying any custom hardware initialization until after the kernel has booted, if at all possible. In this manner, you can rely on the well-known device driver model for access to custom hardware instead of trying to customize the much more complicated assembly language startup code. Numerous undocumented techniques are used at this level. One common example of this is to work around hardware errata that may or may not be documented. A much higher price will be paid in development time, cost, and complexity if you must make changes to the early startup assembly language code. Hardware and software engineers should discuss these facts during early stages of hardware development, when often a minor hardware change can lead to significant savings in software development time ...» |
Код для вставки книги в блог HTML
phpBB
текст
|
|