Michael Kerrisk (man-pages) dixit: >So, the manual page already has the info below. And from your mail >above, it's not immediately clear to me what you would like to see >added. Could you provide a concrete example for a specific >architecture? Sure. I’m using i386 as I’m the most familiar with it. > Arch/ABI arg1 arg2 arg3 arg4 arg5 arg6 arg7 Notes > ────────────────────────────────────────────────────────────── > i386 ebx ecx edx esi edi ebp - This is syscall args. It doesn’t say how userspace args are handled (not in registers by default, but the return value is in edx:eax normally), nor which registers are caller-saved (eax, ecx, edx) or callee-saved (ebx, ebp, esi, edi). Add the name of the stack pointer register (here esp) and you have additionally mapped out the entire basic register file. https://en.wikipedia.org/wiki/X86_calling_conventions#List_of_x86_calling_conventions (look at IA-32 / cdecl) has more information, I guess, but that’s the most important ones. (It’s also incorrect; many Unix systems only align the stack to 4 bytes, and 64-bit values are returned in EDX:EAX, not EAX:EDX, on either.) Some architectures have a more complex register file involving renaming on function call (IIRC sparc does this); this is something I’d also like to see mentioned. Anything more complex the user would still need to look up, but even having this much would enable really fast lookup of the basics that are surprisingly hard to track down for all architectures as there doesn’t seem to be a single place for this. (I recently had to fix something on sh4 and wished for it.) Thanks, //mirabilos -- When he found out that the m68k port was in a pretty bad shape, he did not, like many before him, shrug and move on; instead, he took it upon himself to start compiling things, just so he could compile his shell. How's that for dedication. -- Wouter, about my Debian/m68k revival
