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Data, however, may be retrieved from any address in memory, and may be one byte or longer depending on the instruction. CPUs generally access data at the full width of their data bus at all times. To address bytes, they access memory at the full width of their data bus, then mask and shift to address the individual byte.
With memory protection, only the program's own address space is readable, and of this, only the stack and the read/write portion of the data segment of a program are writable, while read-only data allocated in the const segment and the code segment are not writable. Thus attempting to read outside of the program's address space, or writing to a ...
Core dumps can save the context (state) of a process at a given state for returning to it later. Systems can be made highly available by transferring core between processors, sometimes via core dump files themselves. Core can also be dumped onto a remote host over a network (which is a security risk). [11]
Illegal accesses and invalid page faults can result in a segmentation fault or bus error, resulting in an app or OS crash. Software bugs are often the causes of these problems, but hardware memory errors, such as those caused by overclocking , may corrupt pointers and cause valid code to fail.
The SIGQUIT signal is sent to a process by its controlling terminal when the user requests that the process quit and perform a core dump. SIGSEGV The SIGSEGV signal is sent to a process when it makes an invalid virtual memory reference, or segmentation fault , i.e. when it performs a seg mentation v iolation.
The GNU Debugger (gdb) can be used to look inside core dumps (called CORE) from various supported systems. Gdb is an interactive command-line debugger; [1] various [GUI]] front-ends can be run with gdb.
An address bus is a bus that is used to specify a physical address. When a processor or DMA-enabled device needs to read or write to a memory location, it specifies that memory location on the address bus (the value to be read or written is sent on the data bus). The width of the address bus determines the amount of memory a system can address.
Invalid data or code has been accessed An operation is not allowed in the current ring or CPU mode A program attempts to divide by zero (only for integers; with the IEEE floating point standard, this creates an infinity instead).