Christopher Hallinan: Embedded Linux Primer: A Practical, Real-World Approach

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Of course, your compiler also needs to know the location of target files such as architecture-specific system and library header files.

We will use the term system call, but fork() in this context is actually the C library function which in turn calls the Linux sys_fork() system call.

Refer back to Listing 14-5 in Chapter 14.

Refer back to Listing 14-5 in Chapter 13

By "homes," we mean a public source code repository, such as a web server on the Internet.

By convention, parameters in C are passed in these PowerPC registers.

The AMCC PPC405 is a perfect example of this. The interested reader is encouraged to examine the BAT registers in this processor.

Refer to the Programming Environments Manual referenced at the end of this chapter for details of the PowerPC DSI exception.

The initial ramdisk, or initrd, was introduced in Chapter 6.

We introduced the System.map file in Chapter 4.

For details of PPC assembly language syntax, see Section 16.5.1, "Suggestions for Additional Reading" at the end of this chapter.

Each method has its own roots. The struct bd_info originated in U-Boot, and struct bi_record was an attempt to unify across all platforms. Both are supported by many platforms.

To preserve space, we temporarily removed many machine types in Figure 16-4 prior to LITE5200.

We neglect the context switching time for interrupt processing because it is often negligible compared to interrupt off time.

Robert Love explains bottom-half processing in great detail in his book Linux Kernel Development. See Section 17.5.1, "Suggestions for Additional Reading," at the end of this chapter for the reference.

Interestingly, there is much debate on the correct spelling of preemptable! I defer to the survey done by Rick Lehrbaum on www.linuxdevices.com/articles/AT5136316996.html.

Also called HARDIRQs.

See Linux Kernel Development, referenced at the end of this chapter, to learn more about softirqs.

See www.rdrop.com/users/paulmck/RCU/ for an in-depth discussion of RCU.

We refer you again to Robert Love's book for an excellent discussion of the O(1) scheduler, and a delightful diatribe on algorithmic complexity, from which the notation O(1) derives.