But what’s difference between section and segment? Exactly what you quoted: the segments contain information needed at runtime, while the sections contain information needed during linking. does a segment contain one or more sections? A segment can contain 0 or more sections. Example: readelf -l /bin/date Elf file type is EXEC (Executable file) Entry point … Read more
You only need to worry about ABIs when you are crossing library boundaries. Within your own applications/libraries the ABI doesn’t really matter as presumably all your object files are compiled with the same compiler version and switches. If you have a library compiled with ABI1 and an application compiled with ABI2 then the application will … Read more
Is this actually an ABI requirement, or maybe it’s just some pessimization in certain scenarios? One example is System V Application Binary Interface AMD64 Architecture Processor Supplement. This ABI is for 64-bit x86-compatible CPUs (Linux x86_64 architecure). It is followed on Solaris, Linux, FreeBSD, macOS, Windows Subsystem for Linux: If a C++ object has either … Read more
Stack growth doesn’t usually depend on the operating system itself, but on the processor it’s running on. Solaris, for example, runs on x86 and SPARC. Mac OSX (as you mentioned) runs on PPC and x86. Linux runs on everything from my big honkin’ System z at work to a puny little wristwatch. If the CPU … Read more
The short answer to this question is don’t. Because there’s no standard C++ ABI (application binary interface, a standard for calling conventions, data packing/alignment, type size, etc.), you will have to jump through a lot of hoops to try and enforce a standard way of dealing with class objects in your program. There’s not even … Read more
Choosing four argument registers on x64 – common to UN*X / Win64 One of the things to keep in mind about x86 is that the register name to “reg number” encoding is not obvious; in terms of instruction encoding (the MOD R/M byte, see http://www.c-jump.com/CIS77/CPU/x86/X77_0060_mod_reg_r_m_byte.htm), register numbers 0…7 are – in that order – ?AX, … Read more
Which combinations of these objects is it and isn’t it safe to link into a single binary? Why? For GCC it is safe to link together any combination of objects A, B, and C. If they are all built with the same version then they are ABI compatible, the standard version (i.e. the -std option) … Read more
For small structs (eg point, rect) passing by value is perfectly acceptable. But, apart from speed, there is one other reason why you should be careful passing/returning large structs by value: Stack space. A lot of C programming is for embedded systems, where memory is at a premium, and stack sizes may be measured in … Read more
Because the CPU can’t address anything smaller than a byte.