Bus Error C Code
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Bus Error In C Program
hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss c bus error core dumped Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up What is a bus bus error linux error? up vote 155 down vote favorite 49 What does the "bus error" message mean, and how does it differ from a segfault? c unix segmentation-fault bus-error share|improve this question edited Oct 18 '15 at 10:44 Cool Guy 15.8k51952 asked Oct 17 '08 at 14:48 raldi 7,239216178 add a comment| 15 Answers 15 active oldest votes up vote 150 down vote accepted Bus errors are
Bus Error 10 Mac
rare nowadays on x86 and occur when your processor cannot even attempt the memory access requested, typically: using a processor instruction with an address that does not satisfy its alignment requirements. Segmentation faults occur when accessing memory which does not belong to your process, they are very common and are typically the result of: using a pointer to something that was deallocated. using an uninitialized hence bogus pointer. using a null pointer. overflowing a buffer. PS: To be more precise this is not manipulating the pointer itself that will cause issues, it's accessing the memory it points to (dereferencing). share|improve this answer edited Oct 17 '08 at 15:18 answered Oct 17 '08 at 15:12 bltxd 5,70322336 52 They aren't rare; I'm just at Exercise 9 from How to Learn C the Hard Way and already encountered one... –11684 Mar 26 '13 at 20:12 5 Another cause of bus errors (on Linux anyway) is when the operating system can't back a virtual page with physical memory (e.g. low-memory conditions or out of huge pages when using huge page memory.) Typically mmap (and malloc) just reserve the virtual address space, and the kern
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Bus Error (core Dumped) Ubuntu
only takes a minute: Sign up Bus error vs Segmentation fault up vote 25 down vote favorite 8 Difference between a bus error and a segmentation fault? Can it happen that a program gives a seg fault and stops http://stackoverflow.com/questions/212466/what-is-a-bus-error for the first time and for the second time it may give a bus error and exit ? c share|improve this question edited May 2 '12 at 12:04 casperOne 58k10126202 asked May 8 '09 at 6:56 Thunderboltz 6253915 add a comment| 6 Answers 6 active oldest votes up vote 34 down vote accepted On most architectures I've used, the distinction is that: a SEGV is caused when you access memory you're not meant to (e.g., outside of your address space). http://stackoverflow.com/questions/838540/bus-error-vs-segmentation-fault a SIGBUS is caused due to alignment issues with the CPU (e.g., trying to read a long from an address which isn't a multiple of 4). share|improve this answer answered May 8 '09 at 7:06 paxdiablo 488k1179691416 10 Memory mapped files can also generate SIGBUS. –bk1e May 8 '09 at 16:06 on arm SIGBUS can occur if you read a float from an address that is not 4 byte aligned –shoosh Mar 30 at 7:29 shoosh, I'm pretty certain that's covered by my second bullet point. –paxdiablo Mar 30 at 13:28 add a comment| up vote 11 down vote SIGBUS will also be raised if you mmap() a file and attempt to access part of the mapped buffer that extends past the end of the file, as well as for error conditions such as out of space. If you register a signal handler using sigaction() and you set SA_SIGINFO, it may be possible to have your program examine the faulting memory address and handle only memory mapped file errors. share|improve this answer answered May 8 '09 at 16:04 bk1e 17.9k43760 add a comment| up vote 5 down vote For instance, a bus error might be caused when your program tries to do something that the hardware bus doesn't support. On SPARCs, for instance, trying to read a multi-byte value (such as an int, 32-bits) from an odd address generated a bus error. Seg
challenged and removed. (July 2015) (Learn how and when to remove this template message) In computing, a bus error is a fault raised by hardware, notifying an operating system (OS) that a process is trying to access memory that the CPU cannot physically address: an invalid https://en.wikipedia.org/wiki/Bus_error address for the address bus, hence the name. In modern use on most architectures these are much rarer than segmentation faults, which occur primarily due to memory access violations: problems in the logical address or permissions. On POSIX-compliant platforms, http://forums.devshed.com/programming-42/difference-seg-fault-core-dump-bus-error-174417.html bus errors usually result in the SIGBUS signal being sent to the process that caused the error. SIGBUS can also be caused by any general device fault that the computer detects, though a bus error rarely means that the bus error computer hardware is physically broken—it is normally caused by a bug in a program's source code.[citation needed] Bus errors may also be raised for certain other paging errors; see below. Contents 1 Causes 1.1 Non-existent address 1.2 Unaligned access 1.3 Paging errors 2 Example 3 References Causes[edit] There are at least three main causes of bus errors: Non-existent address[edit] Software instructs the CPU to read or write a specific physical memory address. Accordingly, the CPU sets this physical address bus error c on its address bus and requests all other hardware connected to the CPU to respond with the results, if they answer for this specific address. If no other hardware responds, the CPU raises an exception, stating that the requested physical address is unrecognized by the whole computer system. Note that this only covers physical memory addresses. Trying to access an undefined virtual memory address is generally considered to be a segmentation fault rather than a bus error, though if the MMU is separate, the processor can't tell the difference. Unaligned access[edit] Most CPUs are byte-addressable, where each unique memory address refers to an 8-bit byte. Most CPUs can access individual bytes from each memory address, but they generally cannot access larger units (16 bits, 32 bits, 64 bits and so on) without these units being "aligned" to a specific boundary (the x86 platform being a notable exception). For example, if multi-byte accesses must be 16 bit-aligned, addresses (given in bytes) at 0, 2, 4, 6, and so on would be considered aligned and therefore accessible, while addresses 1, 3, 5, and so on would be considered unaligned. Similarly, if multi-byte accesses must be 32-bit aligned, addresses 0, 4, 8, 12, and so on would be considered aligned and therefore accessible, and all addresses in between would be considered unaligned. Attempting to access a unit larger than a byte at an unaligned address
Search Username Password Remember Me? Register Lost Password? facebook google twitter rss Free Web Developer Tools Advanced Search Forum Programming Languages C Programming difference between seg fault core dump bus error Thread: difference between seg fault core dump bus error Share This Thread Tweet This + 1 this Post To Linkedin Subscribe to this Thread Subscribe to This Thread August 14th, 2004,01:16 PM #1 No Profile Picture Technical View Profile View Forum Posts Registered User Devshed Newbie (0 - 499 posts) Join Date Aug 2004 Posts 1 Rep Power 0 difference between seg fault core dump bus error Hello C experts, Can I have 3 programs for producing the following errors ? 1. Segmentation fault 2. Core dump 3. Bus error I guess to get case one, *p='a' where p has not been allocated memory will do. How about the others ? Thanks in advance. Faq Reply With Quote August 14th, 2004,01:33 PM #2 DaWei_M View Profile View Forum Posts Visit Homepage Lord of Dorkness Devshed Supreme Being (6500+ posts) Join Date Jan 2004 Location Central New York. Texan via Arizona, out of his element! Posts 8,524 Rep Power 3316 1. Segmentation fault. Attempting to access memory in a segment one isn't allowed to access. 2. Core dump. Typically, an error which causes the OS to dump some contents of memory for trace purposes (often the stack). 'Core' was originally a memory technology which consisted of ferrite (magnetic) toroids with windings to set their direction of magnetization and a sense winding to read the current direction of magnetization. It generally just refers to any memory nowadays. The last core I used was a 256K module about 6 x 10 inches occupying the width of a couple PCI slots in today's PCs. 3. Bus Error. The most common cause is an invalid address alignment reference, although attempting to access a non-existent item at a particular bus address can also produce the fault. EDIT: Core in the original sense is non-volatile. It retains its contents when power is off, like CMOS, but doesn't need a battery. Put your OS in there, voila, no boot required! :D Last edited by DaWei_M; August 14th, 2004 at 02:01 PM. Functionality rules and clarity matters; if you can work a little elegance in there, you're stylin'. If you can't spell "u", "ur", and "ne1", why would I hire you? 30