Bus Error Causes
Contents |
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 bus error 10 memory that the CPU cannot physically address: an invalid address for the address bus, bus error c++ hence the name. In modern use on most architectures these are much rarer than segmentation faults, which occur primarily due bus error linux to memory access violations: problems in the logical address or permissions. On POSIX-compliant platforms, bus errors usually result in the SIGBUS signal being sent to the process that caused the error. SIGBUS can also be bus error core dumped caused by any general device fault that the computer detects, though a bus error rarely means that the 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
Bus Error 10 Mac
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 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 addre
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more
Fortran Bus Error
about Stack Overflow the company Business Learn more about hiring developers or posting python bus error ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack bus error (core dumped) ubuntu 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 error? up vote 155 down vote favorite https://en.wikipedia.org/wiki/Bus_error 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 rare nowadays on x86 and occur when your processor cannot even http://stackoverflow.com/questions/212466/what-is-a-bus-error 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 kernel assigns the physical memory on demand (so called soft page faults.) Make a large enough malloc, and then write to enough of i
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow http://stackoverflow.com/questions/2069450/how-to-get-a-bus-error Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss 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 How to get a “bus error”? up vote 12 down vote favorite 1 I am trying very hard to get a bus error. One way is misaligned access and I have tried the examples given here and here, but no error for me - the programs execute just bus error fine. Is there some situation which is sure to produce a bus error? c++ bus-error share|improve this question edited Jan 15 '10 at 9:50 asked Jan 15 '10 at 4:06 Lazer 24.9k65210309 2 What platform and hardware architecture are you using? –R Samuel Klatchko Jan 15 '10 at 5:32 it should be noted that by default x86 will not have a bus error, instead it will work but the memory access will be not as performant as an aligned read. on the other hand bus error 10 SPARC arches do have a bus error. –Evan Teran Jan 15 '10 at 6:50 1 No, see Michael Burr's comments and my answer. Even on x86, you can get a bus error by attempting to access memory which does not exist (as opposed to a segmentation fault, which comes from a violation of access policy). –ephemient Jan 16 '10 at 16:29 add a comment| 11 Answers 11 active oldest votes up vote 11 down vote accepted Bus errors can only be invoked on hardware platforms that: Require aligned access, and Don't compensate for an unaligned access by performing two aligned accesses and combining the results. You probably do not have access to such a system. share|improve this answer answered Jan 15 '10 at 4:09 Ignacio Vazquez-Abrams 444k63792950 is there some way to be sure of that? –Lazer Jan 15 '10 at 4:11 @eSKay: If you're using an Intel CPU, which means basically any personal computer nowadays, you will never get a bus error from misaligned access. If you're using PowerPC, SPARC, etc., then you can cause a bus error that way. –Chris Jester-Young Jan 15 '10 at 4:13 2 Do you have any SPARC or MIPS equipment? –Ignacio Vazquez-Abrams Jan 15 '10 at 4:13 yes, I am using Intel P4. Any idea why no error on Intels? –Lazer Jan 15 '10 at 4:14 3 There are typically other ways a bus error can occur than just unaligned memory access. It's very platform specific as to what causes a bus er