Signals and interrupts a comparison
interrupt, isr, linux, posix, signals
Solution
Interrupts can be viewed as a mean of communication between the CPU and the OS kernel. Signals can be viewed as a mean of communication between the OS kernel and OS processes.
Interrupts may be initiated by the CPU (exceptions - e.g.: divide by zero, page fault), devices (hardware interrupts - e.g: input available), or by a CPU instruction (traps - e.g: syscalls, breakpoints). They are eventually managed by the CPU, which "interrupts" the current task, and invokes an OS-kernel provided ISR/interrupt handler.
Signals may be initiated by the OS kernel (e.g: SIGFPE, SIGSEGV, SIGIO), or by a process(kill()). They are eventually managed by the OS kernel, which delivers them to the target thread/process, invoking either a generic action (ignore, terminate, terminate and dump core) or a process-provided signal handler.
Problem
Based on various references, my subjective definition of signals in Linux is "The triggers that are used to notify the processes about an occurrence of a specific event.Event here may refer to a software exception.Additionally signals may also be used for IPC mechanisms." The questions I have are - I presume only exceptions (software interrupts) are notified via signals.What about the case of hardware interrupts. - What are the various sources of the signal? To me it looks like kernel is always the source of a signal.(except when used for IPC) - Difference between the signal handler and the ISR?. - Difference between signal blocking and interrupt masking?