What directives should I use in GAS? I’ve found the ‘.org’ directive but GAS doesn’t seem to have a ‘.bits’ directive. The assembler defaults to 64–bit for me, you can use –32 or –64 to chose on the command line. Have a look at the manual for as to see how you can change the … Read more
IACA Analysis Using IACA (the Intel Architecture Code Analyzer) reveals that macro-op fusion is indeed occurring, and that it is not the problem. It is Mysticial who is correct: The problem is that the store isn’t using Port 7 at all. IACA reports the following: Intel(R) Architecture Code Analyzer Version – 2.1 Analyzed File – … Read more
See also this excellent LWN article about system calls which assumes C knowledge. Also: The Definitive Guide to Linux System Calls (on x86), and related: What happens if you use the 32-bit int 0x80 Linux ABI in 64-bit code? C is the language of Unix systems programming, so all the documentation is in terms of … Read more