Debugging Bus Error Linux
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Bus Error In Linux Terminal
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How To Solve Bus Error In Linux
Sign up What is a bus error? up vote 156 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
Linux Bus Error Core Dumped
10:44 Cool Guy 15.8k51952 asked Oct 17 '08 at 14:48 raldi 7,249216178 add a comment| 15 Answers 15 active oldest votes up vote 151 down vote accepted Bus errors are 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 ubuntu bus error 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 5,72322336 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 it and you'll get a bus error. –Eloff Jul 14 '15 at 0:09 add a comment| up vote 58 down vote A segfault is accessing memory that you're not allowed to access. It's read-only, you don't have permission, etc... A bus error is trying to access memory that can't possibly be there. You've used an address that's meaningless to the system, or the wrong kind of address for that operation. share|improve this answer answered Oct 17 '08 at 14:55 Clinton Pierce 6,91394576 add a commen
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and bus error c++ policies of this site About Us Learn more about Stack Overflow the how to debug bus error company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags bus error vs segmentation fault 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 http://stackoverflow.com/questions/212466/what-is-a-bus-error takes a minute: Sign up Debugging SIGBUS on x86 Linux up vote 9 down vote favorite 2 What can cause SIGBUS (bus error) on a generic x86 userland application in Linux? All of the discussion I've been able to find online is regarding memory alignment errors, which from what I understand doesn't really apply to x86. (My code is running on http://stackoverflow.com/questions/2089167/debugging-sigbus-on-x86-linux a Geode, in case there are any relevant processor-specific quirks there.) linux debugging bus-error sigbus share|improve this question asked Jan 18 '10 at 20:58 Josh Kelley 34.3k1274147 add a comment| 6 Answers 6 active oldest votes up vote 12 down vote accepted You can get a SIGBUS from an unaligned access if you turn on the unaligned access trap, but normally that's off on an x86. You can also get it from accessing a memory mapped device if there's an error of some kind. Your best bet is using a debugger to identify the faulting instruction (SIGBUS is synchronous), and trying to see what it was trying to do. share|improve this answer answered Jan 18 '10 at 21:10 Chris Dodd 2,274710 1 The debugger showed that the SIGBUS occurred immediately upon entering the function. Maybe I have some memory corruption, or maybe one of the function parameters is bad? I'll have to check the disassembly in the debugger for more details if the error occurs again. –Josh Kelley Jan 18 '10 at 22:13 1 @Josh -- check t
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 https://en.wikipedia.org/wiki/Bus_error is trying to access memory that the CPU cannot physically address: an invalid http://www.unix.com/unix-for-dummies-questions-and-answers/3109-bus-error.html 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, bus errors usually result in the SIGBUS signal being sent to the process bus error 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 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 bus error in 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 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
& Answers This forum is closed for new posts. Please post beginner questions to learn unix and learn linux in this forum UNIX for Beginners Questions & Answers Search Forums Show Threads Show Posts Tag Search Advanced Search Unanswered Threads Find All Thanked Posts Go to Page... linux operating commands and unix operating commands Bus Error UNIX for Dummies Questions & Answers Thread Tools Search this Thread Display Modes #1 11-09-2001 LivinFree Goober Extraordinaire Join Date: Jul 2001 Last Activity: 16 June 2011, 4:50 PM EDT Location: Portland, OR, USA Posts: 1,626 Thanks: 2 Thanked 15 Times in 13 Posts Bus Error This may belong in the C Programming forum, but here goes anyway... What would cause a bus error? I searched google for a cause, but came up with some conflicting reports... Could it be caused by [lack of] disk space? A lot of the pages I found mentioned linking with the incorrect versions of the library. But in that case, would it compile correctly? Basically, I am curious as to why we had a job dump core on a bus error. It ran nearly to normal completion time, then simply poo-pood. In the case that it may make a difference, it's a job that interfaces with an Oracle database on HP-UX 11. The things that had changed were that the process was recompiled, AND we were at 96% (df -k) on that disk... Not too important for me to know right now, but I am curious, and who wants to wait for developers to tell me what happened? Remove advertisements Sponsored Links LivinFree View Public Profile Find all posts by LivinFree #2 11-09-2001 Perderabo Unix Daemon (Administrator Emeritus) Join Date: Aug 2001 Last Activity: 26 February 2016, 12:31 PM EST Location: Ashburn, Virginia Posts: 9,931 Thanks: 64 Thanked 462 Times in 267 Posts The bus in question is the address buss and it contains an illegal value. This is almost always the result of dereferencing a pointer that contains an illegal value. Here is a program that, I think, will compile with every C or C++ compiler, but should cause a bus error when the second printf is attempted... Code: #ifdef __STDC__ #define PROTOTYPICAL #endif #ifdef __cplusplus #define PROTOTYPICAL #endif #include