Causes Of Bus Error
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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) bus error 10 that a process is trying to access memory that the CPU cannot bus error c++ physically address: an invalid address for the address bus, hence the name. In modern use on most architectures
Bus Error Linux
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
Bus Error Core Dumped
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 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 bus error 10 mac 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 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 the
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Fortran Bus Error
or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x python bus error 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 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 for https://en.wikipedia.org/wiki/Bus_error 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). a http://stackoverflow.com/questions/838540/bus-error-vs-segmentation-fault 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 489k1179701418 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. Segmentation faults happe
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and http://stackoverflow.com/questions/2089167/debugging-sigbus-on-x86-linux 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 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 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 bus error 10 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 to