What is a bus error?

Question

What does the "bus error" message mean, and how does it differ from a segfault?

Answer 1

My understanding is that Segmentation Fault/violation indicates that an instruction is referencing memory it has no business referencing - while a Bus Error indicates an instruction is referencing an address that doesn't exist.

So if a user-space instruction was referencing a "low-memory" address like 0x1000, we would expect a Segmentation Fault/violation.

If an instruction was referencing a fictitious address like 0x10000000000000000000000000, we would expect a Bus Error .... make sense?

Answer 2

Bus error occurs when the process is trying to access an INVALID address: the physical address is not valid, does not exist, is not aligned properly per 8 bits, or out of range.

SegFaults occurs when the process is attempting to access an address that is not allowed, because it is a RESTRICTED area in the memory, including but not limited to, READ ONLY location, OPERATING SYSTEM memory, or on the call stack