What Happens When Your Program Segfaults

Your C program dies with "Segmentation fault (core dumped)" and exit code 139, yet it never printed a word, so who wrote that line? We follow one bad store to address zero: the MMU refuses it, the kernel's page fault handler finds the address in none of the process's memory regions, and instead of killing the program it sends signal 11. We catch that signal, watch a handler get called again and again, see why a stack overflow needs a second stack, and find out how your shell turns 11 into words and 139. Related Videos ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬ How Virtual Memory Works:    • How Virtual Memory Works   How malloc Works:    • How malloc Works   How a CPU Runs Your Code:    • How a CPU Runs Your Code   What Happens When You Press a Key:    • What Happens When You Press a Key   How Unix Pipes Work:    • How Unix Pipes Work   What Happens When You Press the Power Button:    • What Happens When You Press the Power Button   Contents ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬ 00:00 - Who Printed That? 00:28 - One Bad Store 01:41 - Most Faults Are Fine 02:50 - Two Kinds of Bad 03:50 - Signal Eleven 04:54 - Catching It 06:09 - When the Stack Runs Out 07:10 - The Default Action 08:03 - The Shell's Sentence 09:16 - Why Most Bugs Don't Crash #operatingsystems #computerscience #programming