IBM developerWorks: Inline assembly for x86 in Linux

[ Thanks to Kellie
for this link. ]

“Bharata B. Rao offers a guide to the overall use and structure
of inline assembly for x86 on the Linux platform. He covers the
basics of inline assembly and its various usages, gives some basic
inline assembly coding guidelines, and explains the instances of
inline assembly code in the Linux kernel.”

“If you’re a Linux kernel developer, you probably find yourself
coding highly architecture-dependent functions or optimizing a code
path pretty often. And you probably do this by inserting assembly
language instructions into the middle of C statements (a method
otherwise known as inline assembly). Let’s take a look at the
specific usage of inline assembly in Linux. (We’ll limit our
discussion to the IA32 assembly.)”

“Let’s first look at the basic assembler syntax used in Linux.
GCC, the GNU C Compiler for Linux, uses AT&T assembly syntax.
Some of the basic rules of this syntax are listed below. (The list
is by no means complete; I’ve included only those rules pertinent
to inline assembly.)”

Complete
Story