Global variable declaration inside function (Python
If you only want to read (access) the value of a global variable, you do not need the global keyword. Python automatically looks up the variable in the global scope…
Month: November 2025
Why the load of main by _start uses got entry, not adrp+add pair?
The _start function uses a Global Offset Table (GOT) entry to load the address of main primarily because _start is defined in a pre-compiled object file (typically Scrt1.o) that was…
AArch64 Pre/Post Indexing
In AArch64 (ARMv8-A 64-bit architecture), Pre-indexing and Post-indexing are memory addressing modes used with Load (LDR) and Store (STR) instructions. Their primary purpose is to perform Writeback: they automatically update…
Check whether an executable is pure C or CPP
Distinguishing between a pure C and a C++ executable can be achieved by examining the symbols and library dependencies of the binary file. C++ compilers employ a technique called "name…
Setup Docker on Ubuntu 25.10
To set up Docker on Ubuntu 25.10 (Questing Quokka), follow these steps. These instructions use the official Docker repository to ensure you get the latest version. Step 1: Uninstall Old Versions…
PIE Relocation: Tagging Addresses
In a Position-Independent Executable (PIE), absolute addresses aren't "tagged" directly within the machine code. Instead, the linker creates a separate list of instructions and data locations that need fixing, and this…
Understanding Binary File Components
Symbol Table Think of the symbol table as a directory for the "named things" within your code, like functions and global variables. When you compile a source file, the compiler creates an…
Control Dependence Graph and Data Dependence Graph
A Control Dependence Graph (CDG) and a Data Dependence Graph (DDG) are essential tools in computer science, particularly in compiler design and program analysis. They represent the dependencies between different parts of a program's code,…
WordPress site Migration from CentOS7 to Ubuntu24
Phase 1: Preparation on CentOS 7 (Source Server) First, you need to back up your data. Log in to your CentOS server via SSH. 1、Backup the DatabaseRun this command to…
How to reset ZeroTier moon node
ZeroTier Installation ZeroTier provides a script that detects your OS, adds the correct GPG keys and repositories, and installs the package for you. # Install curl (if missing): sudo apt…