Bus Error Core Dumped Assembly
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Bus Error Core Dumped C
other. Join them; it only takes a minute: Sign up What is a bus error? up vote 155 down vote favorite 49 What does the "bus error" message mean, and how does it differ from a segfault? c
Python Bus Error Core Dumped
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 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 bus error core dumped c programming 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 it and you'll get a bus error. –Eloff Jul 14 '15 at 0:09 add a comment| up vote 55 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 th
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
Segmentation Error Core Dumped
CPU cannot physically address: an invalid address for the address bus, hence the name. bus error linux In modern use on most architectures these are much rarer than segmentation faults, which occur primarily due to memory access violations: problems how to debug bus error 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 caused by any general device http://stackoverflow.com/questions/212466/what-is-a-bus-error 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 three main causes of bus errors: Non-existent address[edit] https://en.wikipedia.org/wiki/Bus_error 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 addresses 1, 3, 5, and so on would be considered unaligned. Similarly, if multi-byte accesses must be 32-bi
I'm not pointing my finger at gcc here, this is a Sun gotcha).Here's an example program (simplified for something much more complex that I http://blog.jgc.org/2007/04/debugging-solaris-bus-error-caused-by.html was debugging), that illustrates how memory alignment on SPARC systems can bite you if you are doing low-level things in C. In the example the program allocates space for a thing structure https://trac.ffmpeg.org/ticket/1481 which will be prepended with a header. The header structure has a dummy byte array called data which will be used to reference the start of the thing.struct thing { int bus error an_int;};struct header { short id; char data[0];};struct header * maker( int size ) { return (struct header *)malloc( sizeof( struct header ) + size );}int main( void ) { struct header * a_headered_thing = maker( sizeof( struct thing ) ); struct thing * a_thing = (struct thing *)&(a_headered_thing->data[0]); a_thing->an_int = 42;}If you build this on a SPARC machine you'll get the following error core dumped error when you run it:Bus Error (core dumped)Annoyingly, if you build a debugging version of this program the problem magically goes away and doesn't dump core in the debugger. So you either resort to printf-style debugging or going into gdb and looking at the assembly output.Here's what happens when you run this in gdb (non-debug code):(gdb) runProgram received signal SIGSEGV, Segmentation fault.0x000106d8 in main ()Since you can't get back to the source we're forced to do a little disassembly:(gdb) disassembleDump of assembler code for function main:0x000106b0
BUS error on misaligned memory access on some ARM Reported by: notzed Owned by: Priority: normal Component: build system Version: unspecified Keywords: arm crash SIGBUS Cc: jacob Blocked By: Blocking: Reproduced by developer: no Analyzed by developer: no Description (last modified by cehoyos) By default configure on armv6+ enables misaligned memory accesses using the HAVE_FAST_UNALIGNED define. I think some(?) ARM cpu's have run-time configurable exception behaviour for misaligned memory accesses, and unaligned access causes BUS errors if so configured. On locked android machines this cannot be changed by the user, and in general it's a global system setting so not appropriate to change anyway. Crash is reported for a Tegra 3 tablet - ASUS transformer prime. example crash below, where: ldr r3, [r0, r1, lsr #3] equates to: *((unsigned int *)(r0 + r1 >> 3)) Strangely this error is still quite rare and un-predictable, so I'm not certain this is the cause. But manually disabling HAVE_FAST_UNALIGNED seems to fix it. I don't really know what to suggest, perhaps allow HAVE_FAST_UNALIGNED to be overridden by a configure option. Program received signal SIGBUS, Bus error. [Switching to Thread 12614] mpeg4_decode_block (s=0x1f97f40, block=