Qnx Sigbus Error
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How To Debug Bus Error
resources Priority support plan users guide Standard support plan user's guide HomeSupportKnowledge Base BSPs and drivers BSP directory Supported hardware directory Community resources Product documentation Questions? Contact us Question - what is the expected QNX behaviour if an interrupt hang?Q: ================================================ We have an interrupt handler that handles one of the PPC's external interrupts. This references a hardware address that in some circumstances may how to solve bus error in linux generate a bus fault when accessed (i.e. the read cycle cannot complete). We understand the bus fault will itself generate an exception, which can be handled. The question is what happens to the interrupt handler that generated the bus fault? It can't continue, so does the processor return from the interrupt? Will the next interrupt on the same external line be handled correctly? Will the system lock up? ================================== A: Bus Error. ---> SIGBUS /usr/include/signal.h Reasons:http://en.wikipedia.org/wiki/Bus_error non-existent address unaligned access >We understand the bus fault will itself generate an exception, which can be handled. This cpu exception is handeled by the kernel (procnto) and transformed into a SIGBUS signal and that is made pending onto the process what caused it. And now your question: >The question is what happens to the interrupt handler that generated the bus fault? NOTE: Assuming you have used InterruptAttach() -call your interrupt handler is running (with some priority beyond 255) in kernel space/context not in process space/context and it shares its stack with the kernel. So if this cpu-exception is generated from within your interrupt handler then again the kernel handels it turns it into a SIGBUS signal an
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 sigbus error linux a process is trying to access memory that the CPU cannot physically
Bus Error Vs Segmentation Fault
address: an invalid address for the address bus, hence the name. In modern use on most architectures these are
Bus Error 10 Mac
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 http://www.qnx.com/support/knowledgebase.html?id=50130000000PzDZ 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 below. Contents 1 Causes https://en.wikipedia.org/wiki/Bus_error 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 these units being "aligned" to a specific boundary (the
this post in threaded view ♦ ♦ | Report Content as Inappropriate ♦ ♦ Program received signal SIGBUS, Bus error. I'm working with a large code base and trying to run the http://gumstix.8.x6.nabble.com/Program-received-signal-SIGBUS-Bus-error-td4964554.html program on a gumstix. It compiles successfully, but when I run it on the http://www.gnu.org/s/libc/manual/html_node/Program-Error-Signals.html gumstix, it terminates with "Bus error" Using gdb, I traced it back to one particular function. I'm fairly confident that there is not an error in this particular function. It has been in the code base more than 10 years without changes. It runs on Windows, Linux, QNX, VxWorks, and MicroC/OS. It's been compiled bus error by several versions of Visual Studio and gcc. Nonetheless, here's the function that failed. void build_rotmatrix( double m[3][3], double q[4] ) { m[0][0] = 1.0 - 2.0*( q[2]*q[2] + q[3]*q[3] ); // fails here m[0][1] = 2.0*( q[1]*q[2] - q[0]*q[3] ); m[0][2] = 2.0*( q[1]*q[3] + q[0]*q[2] ); ... } On executing the first line, gdb says "Program received signal SIGBUS, Bus error." The bus error in vectors/matrices in question are statically generated global variables. This code runs on embedded devices with less than 32MB total memory, so a gumstix shouldn't be running out of memory. There's a comment in the code that indicates someone else (who is no longer here) ran into a similar problem and blamed a "bug in TI CodeComposer C6000 v7.2" -- I'm compiling natively on the gumstix using gcc, so I'm skeptical about blaming a compiler. Next, I commented out the code within build_rotmatrix() and ran again. The programs run a good bit further, but the next error pops up in a vector function on the line: vout[i] += T[i][j]*vin[j]; Both problem lines have 2-dimensional arrays. I'm not sure if that's a clue or simply coincidence. I've kept going with some more debugging, but any pointers would be very helpful. -Phillip ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/_______________________________________________ gumstix-users mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/gumstix-users Curtis Olson Reply | Threaded Open this post in threaded view ♦ ♦ | Report
of these signals are indications that your program is seriously broken in some way, and there’s usually no way to continue the computation which encountered the error. Some programs handle program error signals in order to tidy up before terminating; for example, programs that turn off echoing of terminal input should handle program error signals in order to turn echoing back on. The handler should end by specifying the default action for the signal that happened and then reraising it; this will cause the program to terminate with that signal, as if it had not had a handler. (See Termination in Handler.) Termination is the sensible ultimate outcome from a program error in most programs. However, programming systems such as Lisp that can load compiled user programs might need to keep executing even if a user program incurs an error. These programs have handlers which use longjmp to return control to the command level. The default action for all of these signals is to cause the process to terminate. If you block or ignore these signals or establish handlers for them that return normally, your program will probably break horribly when such signals happen, unless they are generated by raise or kill instead of a real error. When one of these program error signals terminates a process, it also writes a core dump file which records the state of the process at the time of termination. The core dump file is named core and is written in whichever directory is current in the process at the time. (On GNU/Hurd systems, you can specify the file name for core dumps with the environment variable COREFILE.) The purpose of core dump files is so that you can examine them with a debugger to investigate what caused the error. Macro: int SIGFPE The SIGFPE signal reports a fatal arithmetic error. Although the name is derived from “floating-point exception”, this signal actually covers all arithmetic errors, including division by zero and overflow. If a program stores integer data in a location which is then used in a floating-point operation, this often causes an “invalid operation” exception, because the processor cannot recognize the data as a floating-point numb