gas

I would like an explanation for the values used with the .cfi_def_cfa_offset directives in assembly generated by GCC. I know vaguely that the .cfi directives are involved in call frames and stack unwinding, but I would like a more detailed explanation of why, for example, the values 16 and 8 are used in the assembly outputted by GCC in compiling the following C program on my 64-bit Ubuntu machine. The C program: #include <stdio.h> int main(int argc, char** argv) { printf("%d", 0); return 0; } I invoked GCC on the source file test.c as follows: gcc -S -O3 test.c . I know that -O3 enables

I want to create a macro like the following: .altmacro .macro assert_eq a, b=%eax LOCAL ok #... .endm To be used as: assert_eq $1 assert_eq $1, %eax I want .altmacro for LOCAL (I see the other possibility of using \@ , but I want LOCAL ). But when I try to compile this I get: Error: % operator needs absolute expression I am guessing that this problem is created by the fact that b=%eax is attempting to use another feature enabled by .altmacro : Expression results as strings , since without .altmacro I could write this without problem. If this is true, how do I escape that for my macro to work?

I have a scenario in GCC causing me problems. The behaviour I get is not the behaviour I expect. To summarise the situation, I am proposing several new instructions for x86-64 which are implemented in a hardware simulator. In order to test these instructions I am taking existing C source code and handcoding the new instructions using hexidecimal. Because these instructions interact with the existing x86-64 registers, I use the input/output/clobber lists to declare dependencies for GCC. What's happening is that if I call a function e.g. printf, the dependent registers aren't saved and restored.

I am writing a bootloader in assembly and it seems to work fine on qemu, bochs and virtualbox. However, it is not loading the kernel on real hardware (it seems). The bootloader starts off by writing a character to the video memory (for debugging), it then reads sector 2 off the drive and far jumps to the kernel. The kernel is then writing some characters to video memory. On a real machine, I see the character from the bootloader on the screen, and there it hangs (blinking caret). I have tried to set DS, ES, SI to zero, and I am also setting up a stack segment. I am reading sector 2 off of the

Is there any way to generate assembly code from C# code? I know that it is possible with C code with GAS, but does anybody know if it's possible with C#? C# is normally compiled to the .NET bytecode (called CIL or MSIL ) and then JIT ("Just In Time") compiled to native code when the program is actually run. There exist ahead of time compilers for C# like Mono's AOT , so you could possibly compile a C# program through one of those and then disassemble it. The result is likely to be very difficult to follow. More likely, you may want to look at the bytecodes which are somewhat higher level than