Disable Hardware & Software Interrupts
assembly, atomic, critical-section, interrupt, x86
Solution
In x86 assembly the the commands are
- `sti` set interrupt enable bit
- `cli` clear interrupt enable bit
These commands set and clear the IF Flag. When the IF flag is set, the CPU will handle hardware interrupts, and when it is clear the CPU will ignore hardware interrupts. It does not affect the handling of non-maskable interrupts though, nor does it affect software interrupts or exceptions. These instructions also don't work in unprivileged mode (usually everything higher than ring 0, depending on IOPL) though.
Problem
Is it possible to disable all interrupts with a ASM/C/C++ program to get full control about the processor? If yes -> how? If not -> how do "atomic" operation system calls work (for example entering a critical section)? Thanks for your help!